If by chance the metal tag and also the upc sticker have been removed from an S10 T5 transmission, it's fairly easy to determine it's gear ratio and approximate year of origin.

The gear ratio is the big factor. A mechanical speedo T5 will have the speedo insert horizontal to the ground while the electronic speedo lines up at an angle slightly up and pointing at the center of the output shaft. Mechanical speedos typically came in S10 T5 boxes up to about 1989 but check the position of the speedo insert in relationship to the output shaft just to be sure. To determine the gear ratio with the transmission out of the vehicle:

1. Put the transmission into 5th gear by shifting from the neutral slot all the way to the right and forward. Turn the INPUT (front splined shaft)a full 360 degree revolution and the rear (OUTPUT shaft) will turn something LESS than 360 degrees. It's HOW MUCH LESS than 360 degrees that will tell you which ratio box you have.

2. Make a mark on the input shaft at a position we'll call 12:00 or "zero" degrees and a similar mark on the OUTPUT shaft at the same 12:00 or "zero" degrees.

3. Rotating the INPUT shaft clockwise 360 degrees while watching the output shaft rotate. The output shaft won't rotate a full 360 degrees.

4. If the output shaft rotates LESS THAN 270 (9:00 position)degrees your 5th gear ratio is .72 and you have a box with a 3.76 1st gear. NOTE BELOW: (See #6 for exception.)

5. If the output shaft rotates MORE THAN 270 degrees you have a box with a .86 5th gear and with a 4.03 1st gear.

6. If the transmission has a tilted rear mount pad and you turn just a little more than 180 degrees you've got a .63 OD T5 probably out of a Camaro and the shifter is all the way to the rear. Check out the tech tip on "Hybrid T5's to prep one of these boxes for your truck.

7. In addition to checking out the gear ratios you also need to be aware that the Ford T5 bolt pattern is different from the S10 pattern so make an impression of your bell housing bolt pattern in cardboard and check this first at the salvage yard.

As a quick "rule-of-thumb" I've found that an BW T5 box that has the output shaft rotating to about the 7:00 position is a .63, about the 8:00 position a .72 and about the 10:30 position a .86.

Another thing I've found is that the vast majority of salvage yard transmissons AREN'T properly ID'd so you'd be well advised to make a couple little marks.....spin and count the shaft rotations, check the speedo insert angle as well as the bellhousing mounting bolt pattern before you plunk down your cash.

Hope this helps you avoid getting a box that doesn't fit your driving and gearing needs.

Dave

BTW......I could have checked 20 T5 transmissions in the time it took to write this ditty. Try it....it's easy and applicable to most any piece of machinery that is geared.

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