David, I have identified at least 7 different head configurations between
the TR2 and 4A.
The earlier TR4A came with a head fitted with steel push rod tubes. The
last of them came with aluminum push rod tubes. The heads are identical
except for the tubes. Sorry I do not know when the changeover occured just
that it is the final head configuration and it initially came with steel
push rod tubes and they later switched to the aluminum tubes. I belive
this is because thay expanded more and made a tighter fit to keep from
leaking thin hot oil.
Take care
TeriAnn
twakeman@scruznet.com
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