Head Gasket Woes!

[sandyman]

Changed gasket on a 1.6 td 1986 t3 and had water pouring out where head meets main engine. Discovered the gasket was protruding out from the seal when took the head off so assumed seal wasn't being created and that's why water was leaking out. Had a mechanic take the head to be checked and the engineer (who's been doing the job 25 years) said it was from an 83/84 engine. Apparently the van did have a new engine put in so it's perfectly possible. In attempting to buy a new gasket i'm really struggling to find a suitable one- i've already got the 3 notch one that would fit the engine i thought it had (1.6td)-is it the same? can someone tell me which to get (part no.) Also how do i check what year the engine is and where do i look? is it possible that the previous owner simply put a 1983 head on a 1986 engine?