identifying early YZ stuff

[Freakshow]

Does anyone know how to identify the yza/b heads and barrels by casting numbers / marks?

IM messing with a bike ATM and its either got either a DT2 head or barrel and a YZ of the other as both are on together but are differant in fit shape so one is one and the other the other, if that makes sence.  But i got no idea whichis which.   Do They have stamp marks cast so can sometell me what they should be if they are YZ.

Also i have come across a YZ360 barrel and webco head, now if the YZA 250 top end fits the DT1, would i be right in assuming the YZ360 top end fit the RT1 or is that just crazy talk.

[facthunt]

YZ250 a/b heads have 4 big holes and 4 for 8mm studs.
YZ360 tops have a wider spacing on the rear studs than RT series so they dont bolt on.
Hope thats helpful.

[Freakshow]

Okay so thats a poo poo on the 360 barrell, but the webco would have the same problem too then ?

any idea on the casting numbers ? to be sure on the 250 stuff is what it is?