Just have an mtdi question as far as the base pump used. If you have a mtdi pump made from a ALH pump, will it fit a AHU engine and vice versa? Are the hardlines and injectors close to the same dimensions on both engines?
One more question, does the AHU pump come in a 11mm variety? Did they even make auto trans' for the mk3 tdis?
I'll answer your easy questions first. The injectors are basically the same. The cracking pressures are slightly different but more or less interchangeable. The injector lines are different but the delivery valves are the same.
A diesel mk3 was only available with a standard transmission. I am not positive but I don't think an 11mm head was ever available on the ahu in North America.
As far as using an alh or an ahu pump for a base, I think all you can use is the internals like the camplate, head assembly, and 20mm input shaft. These pumps don't have the pivot holes for the governor lever assembly for starters. An alh pump can fit on an ahu but the hole in the pump bracket needs to be bored out to the size of the snout on the front of the pump. The ahu pump will bolt up to an alh but the end of the pump is not supported properly. I hope this answers some of your questions and not confusee you instead.
The AHU pump - in France - has a 20 mm diam. main axle. The AFN camplate is the one to use, not sure it is the same as the ALH one. Ever tried Googling BOSCH VE pump (part) numbers ?
The pump 0 460 4x4 ... x digit indicate the unit of the pump head diameter ... (but you already knew it) -
... and swapping pumps has already been evocated here - not 100% sure this was your precise concern, though.