Chrysler three speeds

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There were several three speed tranmissions produced by Chrysler during the sixties and seventies. This is a brief introduction to common three speeds of that era, the A-903, A-745, A-230, A-250, and the A-390.

The A-903 first appeared in 1960 as a standard duty transmission in Valiants as well as slant six Dodges and Plymouths. In the early sixties, it was also used behind some light duty Poly 318 V8s. It was used through about 1972. A-903s used aluminum cases and often came with aluminum bellhousings (as early as 1963). In 1961, a heavy duty version of this transmission was introduced and carried the name A-745. The A-745 was used in taxi and police slant six applications as well as most larger V8 applications (361,383,413) and 100 and 200 series trucks. Contrary to what was published in the Mopar Chassis Manual, The A-745 was not replaced by the A-903. They were used concurrently as the standard and heavy duty counterparts through 1971.

The A-903 and the A-745 are both top loaders (the gearset is loaded in from the top through a cover plate). Externally, A-903 and A-745 transmissions are identical except for the top cover plate. The A-903 uses a flat cover plate and the A-745 uses a cover plate with a bump near the front to accomodate a larger gear assembly. Both use the same bellhousing and orient their shift levers in the same location on the left side of the case.

In the late fifties and early sixties, Chrysler used the Borg Warner built T-87 three speed in trucks and some passenger car applications.

Chrysler introduced three transmissions in the early seventies to replace the A-903 and the A-745. The lightest duty was the A-230. This was a full syncromesh trans with a 8 bolt side cover plate with shifter levers coming through the side cover plate (like a A-833). A-230's were used behind RG, G, and LA engines in either light duty trucks and vans, A-body or B-body applications. The A-230 uses the same bellhousing pattern as the earlier A-903s.

The A-250 was a heavier duty transmission with syncros on 2nd and 3rd. This was used in truck and van applications. The A-250 was a top loader. A third transmission was the A-390. This was a full syncro top loader.

In the sixties, three speeds were common in A, B, and C bodies (not to mention trucks and vans). Three speeds were the standard transmission on most models with four speeds and autos being optional transmissions. Most of the time these were column shift. By the seventies, the only passenger cars receiving three speeds were A-bodies and the occasional odd-ball B-body. Up until 1971, the standard transmission on most C-bodies was a column shift three speed (certain models or engines required automatics). Mid model year 1971, the automatic became the standard transmission and the A-745 was no longer available in a C-body. In contrast, the A-230 three speed transmissions remained the standard transmission on A-bodies through to 1976 (except in 75-76 V8 cars) and standard on all slant six F-bodies through 1980. Supposedly, a column shift A-230 was the standard transmission for all 225 powered B-body Coronet, Monaco, and Satellites through 1978. I recently came across a 1973 Satellite Custom four door with a 225 six and a column shift three speed manual.

Three Speed Ratios

Transmission	1st	2nd	Application
A-903
	3.22	1.84	late sixties 170 A-body
	2.95	1.83	early sixties 170 A-body, all 225 A-body
	2.95	1.83	all years B-body 225
	2.12	1.43	early sixties 318
	2.71	1.83	1961 fullsize 225
A-745
	3.02	1.76	Heavy Duty 225, late sixties 273 and 318.
	2.55	1.49	B/RB applications, early sixties 318.
A-230
	3.02	1.76	A-body, truck, and van.
	3.08	1.70	A-body, F-body.
A-250
	3.18	1.83	Trucks, vans, possibly more.
A-390
	2.99	1.77	Trucks, vans, possibly more.

 

Note that the A-745 and the A-903 share a similar flange shape. Beginning in 1967 and 1968, Chrysler began producing bellhousings drilled to accept multiple transmissions.