The AAZ, AHU, and 1Z vacuum pumps are the same. ALH vac pump is totally different - it bolts onto the end of the camshaft. You could replace the lid. I'm not sure, but I think a lid from the 1.6 rotary pump would work. I've also repaired several by tapping the lid to 1/8" NPT and installing a brass check valve and then a brass nipple to adapt to the correct hose size.