74 Chevy 2 to 4wd conversion

[SuperCooper]

Hello. I'm new to the forum, but I've been looking at this as well. My grandfather bought his 1974 2wd chevy with a straight six new. Papa's been gone a few years now, but "Ole Blue" is still around, and I am now inheriting him. I spend a lot of time in a machine shop and have access to lots of stuff that will come in handy in restoring "Ole Blue." My only problem is that I don't want a 2wd pickup. There's a 4x4 conversion kit available for the GMT400, but there just isn't much info out there on converting the '73-'87 generation from 2wd to 4wd. I've even asked machanics, and they always say "just go buy a 4x4." Then some say it'll be easier to swap bodies with a 4x4. Bottom line, I don't want another 4x4. I want Ole Blue to be my 4x4. I'm willing to pay the price and time. This is something new to me, but I've done other things that were pretty complicated so I think I'll be okay. I figure I'll probably run into a snag or two before it's all said and done, but I'll just feel my way through as I go. So far, by looking at this thread, it looks like I'll need to start with:

-NP205 T-Case
-Not sure, but I assume I'd need some kind of transmission to t-case adapter
-Beefier axles/differential
-Front and Rear Drive Shaft
-Tie Rods?
-At least the front suspension
-Is there anything else?

This stuff seems to be accessible. I've found some of it at LMK...some on Craigslist, etc. I assume most of these parts can be found at salvage yards.

From what I've read the 4x4 conversion kit for the GMT400 actually moves the front axle? Does anyone know if the '74-'87 generation requires any similar modifications? Or is the conversion less complicated than the GMT400? And maybe that's why there's no conversion kit for it? Thank you for any input.

[batty1214]

where it me and I were you(as well as most everyone else) I would find a frame under a truck, and then swap the 2wd truck onto that frame.... much easier.... I did it with a 1970 onto a 69' frame....... did it in 3 long days.

[leolkfrm]

Welcome to the forum
by time you get done old blu will be the sheetmetal only
clen it up fix it up put some decent wheels and tires on it and drive it with pride in the summer only
and buy a 4x4 to play

[batty1214]

Leol has a good point...... how sentimental are you about this truck.....

and leolkfrm.... what part of NY do you come from??

[leolkfrm]

upstate ny

[tjzz4]

Frame is different.... It would take way more fab work than it is worth compared to swapping frames with a complete 4x4 rolling chassis.

[75K30]

Chebbies are soooo easy to convert it is almost silly. The aftermarket is full of goodies to assist us in this type of modification.
What I mean is that you can keep everything associated with your beloved truck, right down to the transmission. You will have to find a couple of specialty parts, and get creative.
Here are a few options:
First I would find a "divorced" or remot mount transfer case. This should be a NP205. I would choose this because it will allow you to use your existing 2wd transmission. You will have to custom fab your own crossmember, but this is easy. I will add that you can simply mount it so that you can run equal length driveshafts. This cuts manufacturing costs, and depending on how extreme you want to get, will only require one spare driveshaft. More on this later. You will have the option to run either a ford style case, a dodge, or a chevy. All had remote mounts available, and only the output shaft makes them different. This becomes important in the next step.
Now you only have to try to install a front axle.
Couple of ways you can do this:
First you have to decide which style suspension you wish to install. You can go the cheap route and install leaf springs. Since the 2wd frames have a slightly different rise in the firewall area, you will have to do your homework and get all of the angles correct.
Some companies offer multi link coilover conversion kits for 4wd vehicle, and these can be modified to install on 2wd's. These are probably the easiest to install, but will be the most expensive.
Further options would be which axle you would use.
You could use a standard full size chevy front axle, and this will get you by. You will have to use a chevy or dodge t-case. These drop on the pass side, and will match the axle.
Once this choice is satisfied, you have a 4wd truck.
Next would be to use a ford front axle, and this means that you would have to use a ford t-case. The advantage here is that the ford axle would be a high pinion axle, and is stronger than any chevy of the same size. This also adds ground clearance, so there are some small advantages here.
After any of these solutions are met, you just have to make up some linkages to shift the t-case. This is a snap. Then you have to make some driveshafts.

About the only troubles that you will have is that your speedo will indicate twice the actual speed when you engage 4wd low range. This can be compensated for by using the speedo drive on the t-case, and not the transmission, but again, this is gravy.

I like this conversion, and I would go for it. Many will look for a complete cab swap, but gramps truck might be just a little more special of you used as much of it as you can. With the options above, there would be nothing that you could not continue to use. It would still use almost all of the original parts.

Ford High pinion Dana 60F in a chevy truck:

[SuperCooper]

Thank you for all your posts! And thank you 75K30! That's exactly what I was looking for, and now that I know it's possible, I can have much more confidence going into this. I've had quite a few people tell me that this is impossible...and if it is possible, it will cost too much. ...but the price doesn't bother me. I was planning to buy a 4x4 anyway, but I'd be so much happier if I could spend that money on this pickup.

My dad has had the pickup in Arkansas for a few years now. I'm planning to bring it back to Oklahoma within the next few weeks and start working on it. The truck will need quite a bit of work, so it'll be a process. First thing is to patch the floor. The poor truck is quickly becoming a flintstone car. Thanks again.

-Seth

[jmlloar]

I've done this swap. It is not hard but it does take ALOT of time. And to do it right you need any 73-87 Chevy truck. the (front) front spring hangers are aligned by using the 4X4 rad support mounts. Did I mention this takes ALOT of time. The (rear) front spring hangers need to be measured out from the front ones. holes drilled and bolted on. Use 7/16 grade 8 fine thread bolts with nylon locknut's in the correct length for each hole. About 2 threads sticking out the nut is perfect. Did I mention the 5 million rivets that need to be removed? The 2X4 front suspension needs to be unbolted. Best to do this in one big chunk just unhook the steering box and idler arm from the frame along with the upper shock bolt. If the engine is still in it needs to be supported for this, because the mounts are attached to the front cross member/suspension assy. Once that is out of the way you can put the 4X4 cross member under the engine but only bolt it to the mounts at this time, not to the frame. It will sit on top for now, Use a c-clamp of vise grips on each side to keep it from sliding. REPLACE the trans with a transfer/trans combo from the donor truck or anything else in this year range but you can also use back to '69 model year for this part. I prefer the 81-87 model for its 208 transfer case. bolt it up to the engine assy with the cross member from the year truck the transfer assy came from. Jack it up till the cross member/mount is touching the frame. Now center the engine in the fan shroud. And center the T/case cross member and drill the holes. I still prefer the fine thread bolts here but you can use the stock bolts. These are usually 3/8 bolts. If you don't have a body lift or a 81 or newer cab you will need the 2 pans out of the 73-80 4X4 pickup one is bolted in one is spot welded in. For clearance for the transfer. If the holes are diff mark new ones for the shifter/ shifters and cut them out. Most other holes are there already. Like if you want to change tranny styles from man to auto the frame bracket holes ect... are already there. Now bolt the front suspension onto the spring hangers, put on the 4X4 steering and brake lines. Bolt up the shocks. (I would recommend using the shock strengthening brackets off of the 4X4 but you don't have to) The rear suspension is easy. Just swap out the spring hangers, springs, and rear end. I did this as a complete assy. Just line up the hanger holes and put in the 7/16 fine thread bolts and nuts as in the front. add some drive shafts, bleed the brakes, check fluids, and have it aligned and you should be ready to drive.

The frame rails on 2wd and 4wd Chevy/GMC trucks are the same only the the drilled holes are different.

P.S. 1 ton trucks dont share the frame of the 1/2 and 3/4 ton models but the axles will bolt right in.