Have decided to post this in case it may be of use... In my quest to find a cheaper than penta alternative circ pump for an aq 125a I bought a automotive volvo part from e-bay for £15.00,"great" i thought, all i wanted to do was change over the guts of the pump but soon discovered the internals will only press out one way,unlike the original,so the mechanical seal had to come off first. This turns out to be glued to the shaft and is almost impossible to remove undamaged so I cut the pump in half with a hack saw to try and salvage the seal only to find I had broken it on my earlier attempts. No problem i thought ,"I'll just buy a seal on line" , no you won't , pump repairers all over the planet will not sell you this item period.
You can however buy it from China surprise surprise ,but only if you buy 50 of them. So I had no option but to stump up the £200 fee and buy penta part, on opening the box,I discovered to my horror,the new pump was the same as the one I cut in half except the port that goes to the heat exchanger had been completely cut off and replaced by a aluminium spigot to enable connection using a piece of rubber hose onto the outside of the exchanger connection. As I have a lathe at my disposal ,making the spigot would have been easy and much cheaper ,"if only I had thought outside the box" before reaching for the hacksaw.....