From: doctorduke_REMOVE_507547_THIS_@yahoo.com
The CV four and five speeds BOTH have a unique seven tooth drive gear
(yellow) that is ONLY compatible with the 23T and 25T driven gears
used for the 3.73 and 4.10 axles, respectively.
If you use an original CV five speed with the yellow drive gear then
you just use the standard 25T (orange) driven gear if you have a 4.10
axle. If you keep the 3.73 axle, just install the 23T driven gear
from the four-speed.
If you use a T-50 from ANY OTHER GM MODEL, the 25T driven gear is NOT
COMPATIBLE, and if you attempt to use it damage will be done.
Most non-CV T-50s had a brown drive gear and an 18 tooth driven gear.
To get your speedo/odo into accuracy with this setup, the best method
is to use a properly geared external adapter. Any local sppedometer
shop should be able to determine the error compute the adapter ratio
and install a properly configured adapter.
The other choice is to disassemble the four-speed and non-CV T-50 and
install the yellow drive gear from your four speed into the five
speed. The 25T driven gear might still be available from GM or
speedometer shops of the CV community.
Duke
[This is message #10318 by user doctorduke on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]