most sought after tranny GM's famous MUNCIE SM420  4 speed manual

the tranny offers the lowest first gear ratio available - 7.05:1

fully rebuilt and refinished ready to bolt up (bell housing to a 235 included if desired no charge)

$1,000   724-459-5469 or icu812also57@aol.com">oicu812also57@aol.com for more info

will deliver in pa, oh, or md for price of gas.. must ship other places or pick up.

MORE INFO BELOW  

  The "SM" in the transmission's designation stands for Syncrho-Mesh, in the tradition of other GM gearboxes.

The SM420 is a top loaded, top shifting truck style transmission. It enjoys the lowest compound gear of all the common truck transmissions at 7.05:1 and as such it is a popular choice for those wanting a very low crawling gear.

The SM420 features a power-take-off (PTO) port on the driver's side of the case.

The SM420 is fully synchronized in the second through fourth gears. All gears are helically cut except first and reverse, which are spur gears. The SM420 features a conventional "H" shift pattern, with reverse being towards the left side, and down.

The SM420 can be adapted to the popular Jeep (and many IH) transfer cases

the Chevrolet and General Motors SM420 will marry directly to a GM style bellhousing. This includes early (1955-1967) Chevrolet / GMC truck, Chevy car, Buick, Oldsmobile and Pontiac bellhousings . It is important that you measure the locating bore on the bellhousing to confirm the 4-11/16" diameter before performing the swap. If you need to join this transmission to a GM truck bellhousing (versions from 1968-1991) with the 5-1/8" bore, it can be done

While the Muncie 420 can be used with any GM engine having the "regular" GM transmission bolt pattern, this transmission installs more easily with the open bottom Chevrolet bellhousings because the lower holes in the transmission case are threaded rather than drilled for clearance. The threaded hole case cannot be modified, so the lower attaching bolts must be installed from inside the bellhousing.

The 420 may also be made to be compatible with AMC bellhousings. This modification has primarily been developed for conversions replacing the SR4, T4 and T5 Jeep® transmission as used in 1980-1986 CJ vehicles. 1972-1979 AMC 232, 258 I6 and all 304, 360 and 401 V8 engines can also be used with this transmission but must be equipped with a bellhousing, release arm, release bearing, and clutch disc from a 1980-1986 6-cylinder CJ.

The 4.0L Jeep I6 (both Renix and Mopar systems) is adaptable using the same method as above, with the addition of installing a Crank Position Sensor (CPS) into the aforementioned bellhousing. This is a service that we provide affordably and in quick turnaround.

When refilling your 420 with gear oil, choose a GL-4 rated oil instead of GL-5. The latter has a higher sulphur content that is mildly corrosive to the bronze alloy synchros of the this and many other transmissions that do not have composite synchronizers. StaLube and RedLine are brands to look for, among others.

I recommend that you select a conventional lubricant or a para-synthetic in lieu of the full synthetics.