Christmas has arrived again at our house with an exciting gift— a Gear Vendors Overdrive unit! Okay, maybe it wasn’t Santa, but in our ongoing mission to enhance our motorhome, we decided to invest in better fuel efficiency, a smoother ride, and reduced wear on our 454 engine paired with a TH400 transmission. Based on my rough calculations, this $3,500 upgrade should pay for itself in about three years, considering our average mileage and current MPG.

Has anyone in this group installed a GV unit on their vehicle? If so, do you have any tips or concerns? How has it performed for you?

Thanks,
Peter

Peter

I have installed hundreds of these and had them in every truck that I pulled trailers with until the Allison came out in the Chevy. They are worth every dollar you spent for it. Simple to install and very effective, cruising RPM will drop by 600, engine driven accessories will live longer due to lower RPM, your 3-Speed transmission is now capable of six-speeds, everything good!

Take your driveline to an experienced drive line shop to shorten and rebalance.

They used to recommend the GM rear axle lube for the unit, with all of the advances in lubrication technology, I don’t know what is recommended now. If it’s not specified in the manual, call them, the clutch inside thrives on good friction, you don’t want to screw that up. The shimming of the input shaft is CRITICAL too.

We are on our way to church but feel free to call me anytime with any questions that you might have.

Good luck and enjoy!!!
Billy
337-241-5033

Peter, never had one or installed one, but always thought they were a good Idea. When I had seals put in my TH400 the rebuilder said that the Gear vendors overdrive was the way to go. The cost in my case is payback, it is low, I drive 71 so few miles a year it would take at least 10 years.

Sure, will be interested to get your feedback after a few trips.

Of all the things I did to my Regal, the Gear Vendor modification was always high on my list but never got done. I am interested how it goes for your coach. Keep us posted please!

I believe you will love the overdrive .

Thank you for your responses, and special thanks to Billy for your advice and offer to help. I'm waiting for the weather to warm up a bit here in Wisconsin before tackling this project. I’ll be sure to share an update on performance, as we have a road trip planned to the Canadian Rockies and Montana while towing a Jeep CJ7. Hopefully, we'll see better mileage this time since we only got around 5 MPG last year.

Peter
I installed one in our 89 regal a couple of years ago. It came with the regal when I purchased it. I have no clue as to the mileage before the install and I have only checked it once afterwards. On a trip from Asheville NC and Charleston SC it got 7.65 miles per gallon towing a Jeep tj.
Check the alignment of the drive shaft after installing, I had to shim the transmission mount about 5/16 to correct. I used large 1/2 fender washers, slotted so they would slide in. As a side note I have not installed the controller, I just wired with a toggle switch, forward on-back off.
I think you will notice a lot less engine noise in overdrive, and will be surprised with the way it preforms.

br