[goatwgn]

Originally Posted by geeteeohguy

Just swapping in a TH350 for the 2 speed ST300 will be a night and day difference. The car will literally feel like it has 200 more HP. Mainly due to the lousy 1.76 ratio of 1st gear on the ST300. The TH350, being a 3 speed automatic, has about a 2.75 first gear. Regardless, an ST300, while super durable, and original, is a serious performance retarder. It's like running the 440 with your shoes tied together.

X2 on this. TH350 (2.52/1.52/1.0), TH400 2.48/1.48/1.0), both have the "first gear" that the ST300 (1.76/1.0) is "missing". Best modification you can make to the car. There is a reason a lot of GTO buyers bought the manual tranny before 1967. And if you are up to the manual swap, all of them are better geared than the ST300, and are way more fun to drive.

[DHVoorhees]

Just an update to the swap out of the 2 spd to 4 speed stick. I found and purchased a M20 (with shifter assembly) from a 1966 or 67 Camaro Casting #3885010. Ratio: 2.52 / 1.88 / 1.46 / 1.00
I also found some other parts on eBay "Bell Housing, Clutch/Brake pedal assembly, Upper Clutch rod, z-bar, and clutch fork". I'm happy that I could find most of the parts relatively easy, but I'm having problems finding the lower clutch rod that will directly fit a 1966 GTO/LeMans. If anyone has a source for the lower clutch rod or a part number for it I would appreciate it. Now I have to find the hardware, springs, pressure plate and clutch kit.

I found a nice reference page for muncie transmissions and casting numbers which was very helpful.
http://www.5speeds.com/muncie2.htm

Thanks
Daryl