When I had my driveshaft shortened for a "new" transmission, I noticed that it was out of phase. I don't think it was 45 degrees, probably more like 15 or 20, but the senior guy at the shop that I went to said that it was that way for a reason and was very careful to put it back together as it was built.
I think it is probably because the engine is not quite in line with the rear end. From what I've been reading,all Firebird V8s are off-set towards the passenger side in front to allow room for the steering gear box to clear the exhaust manifolds.