Don, there are 3 rear cover/mounting arrangements. Over the years I tried
all 3 on the race car, but I prefer the TR-4A arrangement which is what is
on the race car. The TR-250 rear cover plate (piece that attaches to the
cast iron differential housing with 8 bolts) was the same as the TR-4A.
The mounting piece which attaches to the rear cover plate with 4 studs is
different on the TR-250. The TR-4A mounting bracket had 2 complete circles
which slid up over the rear mounting studs on the chassis. It used the
round rubber bushing on top and below the aluminum mounting bracket (i.e.
used 4 of the same rubber bush to mount the rear of the diff).
The TR-250 mounting bracket attaches to the rear cover plate with 4 studs,
the same as the TR-4A. However, instead of 2 complete circles, the TR-250
mounting bracket uses the same rear rubber mounts as the TR-6, and
therefore has the same design as the TR-6, with 2 fingers coming out on
each side to hold the rubber mount.
On the TR-6 they did away with separate pieces for the rear cover plate and
mounting bracket, and incorporated it into one piece. This casting
incorporates the fingers for mounting the rubber mounts into the rear cover
plate. The mounting fingers are the same as the TR-250, but the cover
plate is deeper, thus providing for a larger gear oil capacity.
Hope this helps. When you figure it out, let me know what you got.
From: Patrick McMullen [SMTP:email@example.com]
Sent: Tuesday, November 23, 1999 4:29 PM
To: Don Marshall
Subject: Re: TR6 diff question
Yes there were two different types of differentials that I know of
for the TR-6. The 1969 cars (and maybe early 70's) had TR-250
differentials while the rest of the lot had the standard
differential. Both used the same gearing and bearings. Only the
covers and mounts were different that I remember. I can't recall
why the difference, but have seen them both at VTR Nationals.
Pat in NC