[Sirrotica]

FWIW, in 1967 GM did the swap for GTO owners and put the 440 ft.lb. rated T400 in these cars. A bone stock one can be broken with a healthy running 400 with street tires, from my own torture testing back in the day. Since you can break a stock T400 with street tires and a warmed over 400, I myself wouldn't recommend a T350 which is even less torque capacity than a stock T400, but the OP can decide for himself.

A short tail T 400 only needs a shortened driveshaft, and move the crossmember back (very easy to do, done at least a dozen of these swaps over the years). Everything else hooks to the T300 lines, shift linkage with minor tweaks to the shift cable bracket which have to be done with a T400 or a T350.

[242177P]

Originally Posted by Sirrotica

FWIW, in 1967 ...

The folks that designed the Powerglide back in 1950 would simply not believe the point to which it has evolved. I love the TH400, but even I have to admit the TH350 is quite capable.

[Sirrotica]

Originally Posted by 242177P

The folks that designed the Powerglide back in 1950 would simply not believe the point to which it has evolved. I love the TH400, but even I have to admit the TH350 is quite capable.

From a core standpoint, the 2 transmissions are going to be near the same price point. GMs engineering department already made the determination over 5 decades ago which transmission was superior in a muscle car.

Any muscle car near 400 CU IN came from the factory with the T400, not the 350, (until the smog era choked engines, where GM reconsidered using a 350 in Trans Ams). The reason was warranty claims, and the 400 would survive long enough to get a muscle car past warranty. In interest of longevity, the monetary investment is going to be close to equal, why wouldn't the OP go for at least what GM deemed adequate at the time the car was new? Shortening the driveshaft a couple inches, and moving the crossmember back a like amount, would surely be worth the added torque capacity to avoid breaking parts.

I fail to understand why when talking muscle cars, and the abuse they sustain, (because that's why people own them in the first place), the attitude is to use inferior engineered parts today, because it might be a little less work, or someone might save a couple hundred or so dollars over the stronger engineered parts.

It might seem like a great idea initially, but when you're laying on your back the second time under the car, removing a broken transmission that you thought would be adequate, the false economy of the original decision somehow fades quickly. I've been there and done it, and comments I post here on PY are a lifetime learned as a mechanic, and muscle car owner of nothing but Pontiac muscle cars, and racing them, and thrashing them for decades. First muscle car owned was a 67 326 HO Firebird bought in 1969 from the dealership I worked at, and I have owned and worked on literally dozens of my own, and other customers Pontiac rides to gain my knowledge and pass on recommendations.

Street use, oval track, autocross, road course, and yes more than a few straight line acceleration contests. Been there, built them, broke them and fixed them until the breakage was at a bare minimum. Conducting the torture testing so others could profit from my testing...……………

My testing program was done from my own wallet and making my living twisting wrenches on my own, and other peoples mostly Pontiac musclecars. The third picture in my signature shows the backdrop of Pontiacs in the late 70s and early 80s of my service station and garage where we specialized in Pontiacs. Now if someone has done more breaking of parts, and cost them more money, and time than my own testing program has, I'll gladly yield to their opinions, fair enough? I'll return to the earlier comment I made, "You can't build too strong, but you can definitely build too weak."

[66sprint6]

We did the TH350 swap as it was just so darn easy., which is what we needed. We don't have a lot of resources to do much else. It certainly does everything we need it to. We were considering the 200-R4, but they are pretty hard to come by used. They haven't been made in a long time. We rarely venture far from home with the car, but if we ever do, it would be nice to have the overdrive. So it's on our wish list for now.