Except for the starter motor bulge (TR2 & 3) and slight modifications to the
removable gearbox mount, these boxes are basically interchangeable as a unit.
The early/late all synchro is interchangeable except the TOB and sleeve for
the two types of clutches, plus the bell housing-to-motor set screws/studs
Many of the TR3 internals were the same part#s as the early TR4s, excluding
changes for 1st gear synchro. (am I the only one who checked every part in
the Factory Parts Books?) Later, the factory decided to change gear
profiles, the engagement dogs, and all sorts of things. The internal part
changes became
more and more frequent towards the end of the TR6 run. (yes, Andrew this one
was
for your boxes of unlabled internal GB parts! ) I was lucky to visit the
factory
service school and parts facility frequently during all this. Many of the
internal
parts should not be mixed between GBs!
The all synchro case (factory part# 201622) was reinforced more than once,
but the # was never changed. Early all synchro cases would not last
a single race weekend, even in the factory cars. Most strange as they looked
at least as strong as the TR2/3A cases.
good luck in advance from a serious racer
P.S. It is not a factor of how many anti-roll bars F and or R that a vehicle
is fitted with, but how such things are coordinated with the chassis as a
whole. The
factory offered a front anti-rollbar for the TR3 for good reason! Too much
rear roll stiffness on a TR2/3B can be more than dangerous, but only
when related to (the) front roll stiffness.
HP vehicular dynamics consultant
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