Were the bolt holes on both sides of the 66 chevelle trans support member close or were the holes on the drivers side sometime open? Or was this only ture on 64 and 65 support members? Thanks,

Well, the holes on one side of my '67's crossmember are open (can't remember which side), I would assume '66 would be then also.

my assembly manual for a 66 shows closed hole on the drivers side. But the support member I have has open sloted holes.

Assembly mnual is correct , pass side open ,

My 66 has the Pass side open.