Replacing The C6 Three Speed With An E4OD Overdrive Transmission

The new project has not even been completed and we are already removing the C6 transmission to make way for a fresh, new E4OD overdrive transmission. The opportunity presented itself when I was out at Miller Auto Salvage in Owensville, MO picking up some parts for the truck when I happened to see a beautiful ’89 F-350 which had just been sold for scrap. It was almost criminal that someone would do such a thing. But their loss was my gain. Out of the truck, I came away with the E4OD, a 1356 transfer case with PTO and another Dana 60 front axle (more on that later). Ford introduced the overdrive tranny a few years after my truck was manufactured. I had long desired some kind of overdrive and had even considered installing a GearVendors unit, but never did. This was my opportunity to really take the project to the next level. It’s one thing to remove, rebuild and replace. It’s another thing entirely to alter, modify and create something brand new.

One thing I don’t do is work on the rebuilding of engines, transmissions and axles. I leave that up to the professionals. In this case, I took the tranny to Transmissions To Go in Arnold, MO to be torn down and rebuilt with steel internals to be ‘bulletproof’. As with the C6, I took the case to Gateway Powder Coating to be painted. Once the rebuild was complete, it was finished off with an extra high capacity transmission oil pan thanks to the continued support of the wonderful crew at Mag-Hytec. What better way to compliment the differential covers than a matching oil pan?

The challenge then became how to support the transmission at the tail housing since the E4OD is several inches longer than the C6. The factory cross-member was no longer viable, however, it did come in handy to support the transmission while a replacement was designed and fabricated.