Hi all, my air con pump is knackered, and my question is does anybody know the differences between the diff models there are, for an example mine is part number 1JO 820 803 F and ive noticed a few for sale, the numbers are all the same but the last letter is different

either a K or L etc etc.
Does anybody know if i can use these different lettered ones, it's jyst a refuse to pay £1300 for VW to fix it when i can get a pump for £30 and fit it myself.
Cheers all, pete