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A Five-Speed Overdrive For Your Old Mopar!

There are now two adapter kits available to allow you to install the popular Borg Warner or Tremec T5 5-speed overdrive in your flathead six Plymouth or Dodge. One has the GM S-10 bolt pattern, the second has the Ford Mustang and 1993-1995 Camaro and Firebird bolt pattern.

There are some things to consider when deciding which box to use. The big S-10 plus is that the shifter is in the most forward position possible. There are many used S-10 transmissions available and those built prior to 1989 have a mechanical speedometer. The common S-10 first gear ratios are 4.03, 3.76, 3.5 and as high as 2.95 in the Camaros and Firebirds .

As shown here, there is some interference with the stock right rear motor mount (1938 & up) using the wider S-10.

The stock Mopar throwout bearing sleeve/collar is too small for the S-10 bearing retainer. You can hone out the sleeve or you can turn down the retainer to fit. You could also sleeve the retainer and use a 1996-2001 Cherokee throwout assembly.

One last option is to simply use a Ford bearing retainer and machine the O.D. of the pilot flange to match the S-10. Most stock Mopar clutch forks fit the 2” wide Cherokee throwout.

The input shaft on the S-10 is shorter than the stock Mopar so the kit includes an Oilite bushing to support the S-10 input pilot.

The shorter shaft also repositions the input splines requiring that a special clutch disc be assembled with a reversed, offset hub to get the input splines deeper into the disc.

The Mustang box has one big problem...unless you have bucket seats the shifter is too far back so you’ll have to buy a second box just to get the S-10 tailhousing and shift parts. On the plus side, Ford has been World Class (WC) since 1985, eight years before the S-10. The WC Mustang box is plentiful and has the more popular 3.35 and 2.95 first gear ratios.

The Ford narrow bolt pattern clears the rear motor mounts on most years of Mopars. Owners of ’46-’52 models report that the Ford adapter requires dimpling the crossmember. A photo comparing the two transmissions appears at the bottom of this page.

A second plus is that the Mustang bearing retainer will accept the Cherokee throwout with no modifications.

Like the S-10, most Mustang input shafts are short, so the kit includes a special Oilite bushing to support the input pilot and a clutch disc with a reversed, offset hub.

A third plus for Ford is that there were some long input shafts in certain Mustangs in 1994-1995. These inputs are 5/8” longer than the shorter Mustang and S-10 inputs and can use a stock clutch disc. The special Oilite pilot bushing is still required.

Here you can see how the S-10 and Mustang transmissions look bolted to the Mopar flathead six motor.

Before you buy any transmission you should consult a reliable 5-speed specialist, like Tom Langdon in Utica, MI (586-739-9601), to help determine which T-5 is best for you!

The kit is priced at $345. plus $17.00 shipping

Price good until May, 2011

Paul Curtis 19319 Candlelight Roseville, MI 48066 - 586-296-2488 pjplymouth@netscape.net

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