Considering a 5 speed swap

[rcbildr]

I'm using my 1960 GMC as my daily driver now and would really like to have a 5 speed in my truck...my commute is 35 miles one way and I could really use an OD transmission to help with the fuel mileage.

I have two options sitting in my shop right now, one is a T5 out of a V6 Camaro and the other is an NV-3500 that came out of a 2wd Chevy truck. The only towing I have really planned for the truck is my 26ft Airstream that weighs just under 4000lbs (according to the factory owners manual).

My GMC has the 305 V6 and most of the information I've seen for the T5 swap is for putting it behind a Chevy engine. I figure the only real difference would be trying to get the clutch to bolt up to the flywheel.

My questions are:

Which transmission would be best to use?

If I use the T5, is there any info on putting it behind the V6?

Is there an adapter plate available to put the NV-3500 behind the V6?

I'm thinking the T5 would be the easiest to use on my GMC because the NV-3500 has the integrated bellhousing....not a big deal there because I can use that transmission in my 67 suburban. Any help/thoughts/info would be greatly appreciated. Thanks!

[jayoldschool]

Your airstream is going to weigh more than 4k when it is loaded for duty. I don't think the T5 will be a great choice for something that is going to tow anything. GM didn't think they were strong enough for a stock 350...

[scottofksu]

I'd have to agree with Jay... Assuming your T-5 is a World Class unit, it is only rated for around 300 lb/ft. Granted, your 305 is probably not putting out that much torque; however, you can also use this rather low limit as an indication of the transmissions strength. The real weakness in the T-5s is the aluminum case, and I think you'll split yours like a dropped melon the first time you come to a sizable hill and the weight of the camper starts pulling back. Not to mention that the Camaro unit will put the shifter around 6 inches behind where the stock unit enters the cab. If you're running a bench seat this will mean that you have to reach under the seat to try to shift...

[Clyde65]

the NV3500 is rated at 330tq. I would look into the S-10's and see if the 5 speeds they had would pull a 4500lb trailer ( im not sure). other option would be an NV450, bigger and stronger.

[Wrenchbender Ret]

The T-5 would be an easy swap but I agree it would not stand up to that kind of use. I put them behind 350,s but don't drive it hard.

[70inline6]

3 spd ODs from the 50s-64? might be your best bet for your double duty plans. The are pretty cheap, bolt right in in place of the standard 3spd, and can take the strain. I and several others are making/made this swap. The toughest part is the simple relay wiring. Just a thought.

Thread here.

I've read your other post about a hitch too, and my thoughts are that the first thing you should do is upgrade to power/dual MC brakes if you're going to be towing anything more than a lawn mower trailer. Be safe. :-)

Brad

[62-One-Ton]

I drive a Silverado with a NV3500 everyday about 250 miles. (yes daily). I usually have about 250-1500 lbs in the bed during all but 60 miles of the 250 for the day. And its been great, no issuses, no complaints. Easy shifting, great ratios for my use. I have no experience with the T-5 but Ive read that they are basically good for a lightly driven street car and thats it. NV3500 would be my choice or even better a T-56 but that wasn't listed on your choices. Im currently seeking a NV3500 for my 5.3 Gen III swap in my '62.
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[rcbildr]

Originally Posted by 70inline6

3 spd ODs from the 50s-64? might be your best bet for your double duty plans. The are pretty cheap, bolt right in in place of the standard 3spd, and can take the strain. I and several others are making/made this swap. The toughest part is the simple relay wiring. Just a thought.

Thread here.

I've read your other post about a hitch too, and my thoughts are that the first thing you should do is upgrade to power/dual MC brakes if you're going to be towing anything more than a lawn mower trailer. Be safe. :-)

Brad

I've considered trying to find a 3spd OD trans, and will start saving/planning to do that. I was curious about what I already had.

The truck has power drum brakes and I thought I might be able to get by with wiring up a brake controller for the trailer brakes. I haven't done much research yet on the brake/master cylinder conversion, and I'm not too sure how to go about it because of the hydraulic clutch and brake master cylinder being all one unit.

I did find a class III hitch at the JC Whitney website and once I have the funds, I might consider buying it....but truthfully my 85 diesel burb is probably the best for heavy towing. I should probably just keep my GMC the way it is and enjoy it.....maybe slap a holley 500 cfm two barrel carb on it and lower the back a couple inches and drive it till I can't drive any more. Thanks!!!