I'm wondering if anyone can tell me if I need to drill new holes for my cross member when I swap a Turbo 400 for the powerglide. I have heard some people say the holes are already there however the 66 never came with a Turbo 400.

Thanks for the help

i was told that you just move the xmember to the back holes. that did not work for me. my 66ss was a 4 speed car, but had a sbc, th350 combo when i bought it. i'm assuming that the xmember was the original piece from the four speed as i have used a th 350 x member before in a 4 speed swap. anyway i had to use a cutting wheel and cut the tranny tab off the front of the xmember and move it to the back and reweld. i then slotted the holes in the tab just alittle more to make it fit. i also lowered the tab about 1/8 of a inch to get alittle more tranny tunnel clearance. hope that helped,but as you said i heard the just move it to the back holes works for some ?

I've converted 4 '66 powerglide Malibu's to th400. All done by sliding the original crossmember back and drilling 2 new holes per side. Never had to alter the crossmembers at all. The '66 not having the option does make for tight tunnel clearances. Maintaining the stock console and linkage usually takes a little manipulation. Either banging some space or shimming the shifter up a bit.

Thanks for the advice, drilling the frame seems the correct option