The project is well underway with our 1949 M68 Mercury pickup, and I'm going back and forth on a transmission choice. I can save a few $ by going with a S10 five-speed, but occasionally I read that this might not hold up on this truck, which is rated as either a 3/4 ton or a 1 ton depending on who you talk to. Any thoughts on that S10 choice?

 

What engine? What rear gears? Planning on towing or hauling loads?

 

255 flathead, planning on something like 3.73 gears (working on gearing ratio that gets us a decent 55 or 60 mph on highway). No loads - maybe some groceries on Sunday afternoon, that kind of thing.

 

Most important things you should consider when using a non-factory matched transmission is 1) how much torque will your engine produce, and 2) how will you use the vehicle.


A 255 flatty is not going to produce enough torque to destroy that trans in one day, but over time it could, but I guess anything could.
And this brings us to the next point: You'll only use the truck as a cruiser, no real truck loads to speak of.

That trans should easily do the job for a long time as long as you don't haul considerable amounts, and go easy on it. No clutch dropping.
If you need to haul you should be fine, just go easy on the girl and don't shift into the 5th OD gear.

 

You probably want to stick to World Class T5's and keep gearing around 4:1 so 5th isn't useless.

 

Thanks mOROTBREATH - that's been my thinking as well but you know how it goes - you never know until you try. Builders around here tell me it will work as long as I don't overload it, which is definitely not the plan.

 

ALBUQf1 - that's definitely the other option I've been going back and forth on. It would give me a more robust solution for sure. Appreciate the insight.

 

You could also consider the top loaded, top shifted four speed from a early 80s F-150. Fourth gear on these is overdrive. This is not a heavy duty transmission, but neither is the T5.

 

There are two types of T5. You want the world class (I believe that is what it is called) T5 if you go that route. It is a heavier duty trans and will hold up even if you haul moderate loads. Have fun

 

Thanks everyone for the advice. I'm going to continue to check the options - the T-5 is readily available as is the S10. I haven't actually consider the 4-speed '80's F-150 transmission, but I'll check around for that as well.

 

49f3lds - it is indeed the "world class", and if I end up going with a T-5 that's the option I will choose based on its rep for being a bigger tougher device