TH350 or TH400 for towing a BP travel trailer

I have a 1974 Chevy pickup with a 4 bolt main 350 built that I built for towing. 350 HP 430 lbs. of torque. Not giant numbers, but it tows our 2 horse trailer loaded with 2 hay burners without any problems. I also have a 24 foot bumper pull travel trailer that is 4700 lbs. that I use to camp. It pulls it fine, but I am worried that the transmission is the weak link.
The truck only has 58,000 original miles and came stock with a 9" tailshaft
TH350. My question is, can a TH350 be built as strong as a TH400? I know that a TH400 takes more power to run because they came behind big blocks a lot from the factory. Plus, it is kind of a pain to change it over to a TH400.

I would think a either trans would do. If I had a T400 I would build it but, the T350 will do the job, and very well at that.

Keith

I agree. Just bump up the cooling system with an in line add on cooler (or a bigger one if you already have one) and maybe add a temp gauge for the transmission. Lots of things have been towed with both transmissions.

Don

I have a TH350 as well but mine is 4 wheel drive with a np205 transfer case, Im looking to add quite a bit of power soon I'm looking to generate around 450 hp with 470 tq, Im not sure if the TH 350 or the 400 will be good for getting the poer to the ground, I do have a preformance kit for the 350, but not sure which tranny would be better??

i think with those torque numbers i would go with the th 400.

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Originally Posted by jbright300

My question is, can a TH350 be built as strong as a TH400?

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Short answer-NO
Long answer-It can be built strong enough for what your doing with a seperate cooler,good parts in the build and not B&M junk,and you dont give 35 ponies to the tranny