The boxes SHOULD interchange. Later boxes had two changes. The splines on the pittman arm changed. That is, later boxes had a larger spline. And, the bolts fixing the box to the K-member were larger on later or bigger cars. If the box you have now bolts in, you're fine. 67 to 64 shouldn't be a problem if it was an A-Body box.
"Research" on Rock Auto shows different pittman arms, although the same "research" dhows the Lares 1033 rebuilt box fits both years/models, with the caveat 'use your original pittman arm'!
I'll measure mine and compare the '67 Cuda one at the sellers. Assuming he has the pittman arm on the box.
My question is the pittman arm geometry the same?
