hey is there any difference between the h22 generation of mani's? can i use any on an obd-1 motor? thanks

 

The castings are identical, manifold to head flange is the same, as are the runners. However the upper section of the manifold that has a few different vacuum outlets. A1 manifolds have and a bypass valve on the upper section as well, and the A4's throttle body has the map sensor on it rather than the firewall.
I have used the A4 manifold on an A1 head, there is no significant difference IMO.