T5 ID.... NWC or NWO 1352-169 ??

[RDMumfts Stang]

Here is what I found on http://www.mustanggt.org/index.htm Go to the Info by Year page and find the GT Transmission Info link and the info below is straight form the chart.

In 1985, the T5 was upgraded to the "World Class" T5 - improvements include:
tapered roller bearings on the countershaft
caged needle bearings under 1st, 2nd, and 3rd gears on the mainshaft
double synchronizers on 1st and 2nd
steel blocker rings with friction linings on 3rd and 4th
torque capacity remains at 265 lbs-ft because of the new 1st gear ratio being 3.35 vs the 1983 1/2 - 1984's 2.95

5-speed T5 (1987-89)7
E6ZR-7003-FB 3.35 1.93 1.29 1.00 0.675 3.15 265 2
5-speed T5 (1989)8
E9ZR-7003-A 3.35 1.99 1.33 1.00 0.675 3.15 300 2

Note: ALL T5's use Mercon Dextron II / III ATF. This is due to the fact it has very tiny oil transfer holes to lube the needle bearings.
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I hope this helps. Note there were two different T-5s used in 89. The latest one having a higher torque rating. Unless yours has been changed, it is a WC.