advice on 5 speed swap, suspension mods on 60-66 panel truck

[Chuck78]

Originally Posted by Jonboy

Chuck, it sounds like you have the perfect donor vehicle already. I was going to try to find an 89-91 Sub to build up my 66 'burb with (when I ever get around to it). I figured on using the engine and trans (going to keep it an auto), front suspension, and anything else I could pirate. I figured on using an aftermarket harness, but mostly because I am lazy.

Yeah, seems like I can make just about everything from my 89 'burb work on my next project. Love that truck, drives great, runs great, 250,000 miles and rides almost like a new truck - other than the extra body flex from the bed and body supports rusting out! That's why I'd love to swap most of it over to a 60-66 panel truck next summer. Just gotta ditch those swirl port heads in favor of some late model vortecs (best small block head chevy ever made, late model trucks up to '99 I believe). Maybe swap in a new RV cam or something fairly mild. And then some Hearthrob or Flowmaster mufflers and headers!

I've pretty much narrowed it down to two trannies now, if I go to manual. The mandatory hydraulic clutch on the NV3500 sounds alright to me. Nice ratios to choose from in a 5 speed as well. Probably would do fine (power handling) with this, but even though it's a bit tougher than a T-5, still not certain on it. I haven't found out about any manual speedo outputs on them (probably never made), but after thinking about it, I would have no problem swapping to an electronic pickup speedometer and tach. Just another cool looking project.
The other tranny would be I believe the 82-86 truck 4 speed that primarily came behind the diesel v8's, with practically the same ratios as a 700R4 (3.09 first and .73 4th?). People complain about 1-2 being a big jump (same with the R4's, not the best for a hi-po engine with a very peaky power curve), but with a 350 (or maybe my spare 400?) with vortecs and a mild RV cam, I think I will have quite a broad powerband that will have no problem on seat of the pants acceleration from any rpm. These things can definitely handle a fair amount of power, as they were primarily a mopar used trans, and (with different ratios) were the trannies from 64+ that were put behind the 440 6 packs and 426 hemi's. These have aluminum cases, some of the mopars had iron cases. Only hangup is no option for a hydraulic clutch without major fabrication and machine work, as the bellhousing bolt pattern is quite an oddball for these GM variatons (MY6 I believe is the code). Kinda half mopar, half GM looking pattern on trans, have to use the matching bellhousing. It's a beast, looks like it'll fit a 12" clutch, definitely works with 11".

These trannies are pretty hard to find nowadays with the GM bellhousing and GM input shaft.

I wonder if there would be any gains to swap in my 89 rear drum brakes in place of the stock 66's? I suppose if they were larger diameter, then go for it. Wonder if the old rears wheel cylinders would be compatible with the 89 master cylinder? Might prefer to track down the older (non-plastic reservoir) master cylinder, suppose that would be easy to match up. Not sure if my differential would have the leafs in the correct place to bolt up to the 66 frame. Also, I think the older leafs were narrower than the newer ones (not sure on specifics), so might have to do a little work, or at minimum re-drilling, to get the 89 leafs to bolt up to the 60-66 frame if I go that route. Might just stick with the coil setup. Not sure what advantage either would have, but most all modern 1/2 and 3/4 ton trucks all have leafs, so I figure that must be for a reason on the utilitarian side of things. It will be mostly a driver but will occasionally haul a car trailer or some equipment, and some heavy loads now and then. Someone on here said something about some air assist shocks or something,t hat you can inflate when carrying a heavy load? Maybe the coils would work out fine with something like that.

Enough for now. Any more advice or opinions?