I bought the wrong transmission for my 66.

So just to get it clear in my mind......your "problem" is that the truck transmission you have needs some work. Is that the main thing, or is it that you cannot put up with the 3.09 1st
Yes, needs work, 3/4 problem, will need rebuilt, maybe more due to the metal,noise. I'm just not happy with the gear ratios. It was kind of doggish with the 2.92 7 1/4 in 2nd and 3rd, it's better with the 3.55 but now the 3.09 is a bit low. The main problem is this box needs fixed or replaced. I thought I was on the right track when I purchased the A body 833 last weekend. Always a solution right?