In 1977 and 1978 there was a late model 3 speed overdrive transmission made for intermediate passenger cars, light duty pickup trucks and vans. This transmission looks just like an early Toploader, but it is not a performance transmission at all.

The tag numbers we know about are:


The casting numbers on the main case or tailhousing start with D7DR for 1977 model. Some of the main cases have an ORION cast on the drivers side. The gear teeth are cut very thin and the ratios are almost the same as an early 3 speed with .85 or so overdrive in 4th.

At first glance it looks just like the real thing.

Toploader in front, overdrive in rear

Here is a view from the front, you will notice there are only 4 bellhousing bolt holes instead of 8 on a true Toploader.

Toploader on right, overdrive on left

When you look inside you will see a little tiny gear where third gear would normally be.  This is actually fourth gear in the 3 speed overdrive transmission.

Toploader on left, overdrive on right

When you look at the shifter mounting holes on the tailhousing you will see that there is no way this tailhousing will work in an early application. The speedometer pickup is also on the wrong side.

Toploader in front, overdrive in rear

On the passenger's side of the main case you will notice a bulge or rib; this is to clear the large OD gear on the cluster.

Toploader on top, overdrive on bottom


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