4wd Conversion?

[jseim44]

As some of you may know, I'm kicking around the idea of making my '69 a 4wd by setting the body on the frame of a '74 highboy. My '69 is a 390 with a C6 and the '74 is a 360 with a C6, so no problems there. In '73 they added 2 inches to the wheelbase. This creates a problem, but I'm prepard to move the rear axle ahead the two inches and get a new driveshaft made. Or do I leave it as is? My grandfather bought it new and it's been handed down. This is already turning into a frame off of sorts..... -Jake

[67nukeford]

Well, Jake, it's yours now buddy, so if that's what you want, then go for it! I don't think your Grandpa would mind!

[tiny1]

Project time!!!!!!

[gquinn8516]

Do what you want - It will always be Gramps truck in your mind.

[jseim44]

I'm going to go over and measure the frame today to confirm what I have been reading. I mentioned it to my brother last night since he'll be helping me with body work and he says "Oh, that could get kind of ugly" when I told him of the wheelbase differences. I don't think it'd really be that bad, just lots and lots of measuring and drilling. We'll see I guess.

-Jake

[jseim44]

I've done the measuring. The width of the frame rails at the rear of both trucks is 34". The wheelbase on the Highboy is 133" and my '69 is 131".

I've been thinking hard about this all morning. Here's a comparison of the two trucks

Highboy:
360/C6/NP203 D44HD front, D60 rear - 4.10 gear ratio. Power steering, power brakes

'69:
390/C6 D60 rear - 3.54 gear ratio. Power steering, power disc brakes

So.......the highboy is a closed knuckle D44 with drum brakes on the front. From what I've read the easiest way to get disks on those closed knuckle axles is to either get a 76-77.5 highboy with disks (don't see that happening) or swapping a complete axle from a later truck with disks on it already. The steering is actually the power ram assist, which I've not really been around but from what I understand is basically manual steering with a hydraulic cylinder to "assist". I've heard it's alright but they usually leak. I'd have move the rear axle ahead and get a new rear driveshaft, and I'd have to drill new holes in the frame for the bed to mount. I'd also have full time 4wd (although conversion kits are available).

My '69 is factory power steering, and factory power disk brakes. I've got some moeny in front coils, a front sway bar, and complete new rear brakes (drums, shoes, wheel cylinders, whole 9 yards) that I'd basically be leaving on the table. I've also got a complete 2wd donor that's basically a twin to it (except for rear axle ratio everything else is the same).

So to make my '69 a highboy I'd have to: swap my 390, swap the body, move the rear axle and get a driveshaft, deal with drum brakes on all 4 corners, deal with the power ram assist steering, and hope that I don't go insane with 4.10's on the highway (although I'd probably run about a 35" tire so it might not be too bad).

Other option is to stick with original plan: swap good parts from '71 to my '69, gain aux rear fuel tank. Maybe pull engine and tranny out of the '71 and keep around for extras. Send what's left of the '71 to the boneyard, or make the '71 complete and sell it.

I just don't know. I really want 4wd but there seems to be alot more cons than pros about doing this swap. It'd also really make it a frankenstein truck, and I've never really been a fan of those.

-Jake

[67nukeford]

Well, guess it's just up to what you want Jake. Either way, I think your good to go!

[Bigredfan]

jake, wouldnt it be eisier to swap transmissions, get a transfercase, and throw a new asxle under the front, all you would have to do is make a couple of shackle mounts and you would be in business. Used to do it all the time when i lived in seattle, a lot of guys do it this way when they convert ifs front suspentions over to solid axle.. same principle

[67nukeford]

He'd have to change the front cross member also. I bet we could find him a 67-72 4x4 frame.

[Bigredfan]

i still think that would be alot easier than a highboy conversion.... just my 2 cents

[PsycoJuana]

Oh man be nice, but a bit of work!

[The Freak]

I wouldn't shy away from the project just because it sounds like a lot of work. If you want a 4wd, then go for it!! The knowledge you'll gain throughout the project and the sense of accomplishment that you'll feel when you get to enjoy it will be second to none. Plus, this time of year, who wants a 2wd??!!!

That being said, is your mind set on making a hi-boy 4wd?? If you're open to other options, I would recommend that you consider finding a 78/79 4wd chassis for your project. Using the newer chassis will eliminate the disc brake issue up front since you will now have a HP 44, and you will also have the better steering setup. But, you won't have a hi-boy/divorced setup when it's all said and done. Also, by using a newer chassis, you could run 3.54's, but everyone that I know runs and recommends 4.10's, especially with a 35" tire.

If you want to keep it old school, that would be cool too, but I think you're going to need to go either one way or the other. I may be able to get my hands on a 69/70 hi-boy. Not sure if the guy still has it or not, but finding out is only a short road trip away for me. He wanted too much for it, or more than I wanted to spend before. Could be a different story now??

[The_SnowMan710]

welp, Jake, personally i would leave it a 2wd b/c i'm

A. Lazy
B. Like original machines
C. Think a 4wd conversion would be easier than a body swap
D. Know a shiny highboy would look better in my driveway
E. ...ran out of reasons...

[jseim44]

OK Kenny....you can come get the highboy. Call me in 20 years when it's still not shiny....

-Jake

[The_SnowMan710]

is that the truck u bought in kearney or where ever u where telling me u and ur brother went?