I have a rebuilt 1968 c4 tranny all put back 2gether. The torque converter turns by hand on the front shaft, but it won't turn by hand at the tail with the yoke hooked up. The original tranny pulled out of my 77 Mav turns by hand and this one has not been touched. Did I do something wrong?
Not necessarily; Will it turn using a pair of channel-lock pliers? With all new friction materials it will be stiff. You have to overcome all that friction to turn it and in one direction you will be fighting the one-way clutch and gearing plus all the friction. Make sure the bands are adjusted properly - just to be on the safe side because if they are too tight it will bind. Check it with the pliers and if it turns, I say bolt it in and run it up.