Any one have any experience with a Gear Vendor? Thinking about one for me 1976 Dodge 360 with TBI. I get 9.5-10 mpg now, hoping for more.

What are your thoughts?

Views: 195

Reply to This

Replies to This Discussion

Good morning, Jack; 

The Gear Vendor 3D0475 Over Drive bolt-onto-the-back of the 3L80 three speed automatic transmission is what I am working toward also.  The plan is to do the engine modifications first to make sure the engine can pull the 22% higher gearing on the level ground, and be able to drop back to standard 3rd for the grades and then 2nd-Over for the steeper climbs.  The calculations say that with this full package, I should be able to go up the West side of Steven's Pass in 2nd-Over at about 50 MPH or maybe 55 MPH instead of the 35-40 MPH that I can climb that hill now with the 15,000 pound weight that I normally run with the P37 motor home chassis. 

If the C-172 comes to an end this winter, and it is looking like it will, because I am not able to pay for the full MOH the O-300B engine is looking at right now, then completing the P37 engine-driveline conversion should be possible by this coming spring.  That will be nice. 

While there is hope for an improvement in fuel economy, my main goal is the use of the over-drive on 2nd and 3rd gears for climbing with 2nd, and hopefully flat land fuel economy with 3rd. 

One thing that I noticed is that I will need to recalibrate the speedometer, or somehow move the speed0meter-odometer cable off the transmission and back to the driveshaft where it will not change as gears are shifted.  One possible work-around I can do right now is to use the GPS box speed display for complying with the speed limits.  Besides, while the speedomoter is accurate, the odometer in my P37 is about 10% optimistic and makes it seem like the 454 in the P37 is getting much better fuel economy than it actually is.  Using the GPS box for a more accurate indication of actual miles traveled was disappointing when I first calculated the fuel economy that way.  It seems that the C-172 actually does get better mileage than the P37. 

Enjoy;  Ralph,   Latté Land, Washington 




  •         How To Links 

-Search Good Old RV's

-Start a New Group 

-Roof Repair Photos & Products

-Repair an RV Roof

-Pick Roof Sealer   

-Understanding RV Electrical Systems 

-Get RV Insurance   

-What to Look For When Buying a Used RV

-Jack Installs Fuel Injection in his Dodge 


 Paige's VintageTrailer Art  

 Paige's VintageTrailerFabric

 Artist Roads                                            Sandy's Stained Glass     



If you love classic and vintage RVs then come Join us. Come on in and have some fun. JOIN HERE NOW

Blog Posts


Posted by Linda Lee Toepfer on January 18, 2021 at 1:40pm

1982 Chevrolet Travel Mate Class A

Posted by Barb Stanley on December 17, 2020 at 9:15am

Looking for help identifying this camper

Posted by Jeff on October 7, 2020 at 12:57am — 1 Comment

Balboa owners

Posted by Bill on May 19, 2020 at 8:11am


Posted by Eddie Marquez on May 5, 2020 at 2:34pm


  • Add Videos
  • View All


If you love classic and vintage RVs then come Join us.

 Come on in and have some fun.         JOIN HERE NOW!

 Dedicated to a simpler, more rewarding and fun way of life in a Good Old RV... 

Vintage Travel Trailers, Vintage Campers, Camper Restoration, Bus Conversions, Vintage RV Forums, Old RVs, Tiny Homes, Boondocking


A work of art by member Paige Bridges

Get your Good Old RVs T-Shirt HERE


 Disclaimer - Please Read it

Enjoy this site and use it totally at your own risk.

By using or viewing this site YOU agree to Hold Harmless anyone associated with it including other members. Also, YOU agree that YOU are solely responsible for ANY and ALL actions, results or damages. Members "opinions" are just that and any repair or alteration comments or recommendations are by folks who are not licensed repair  or mechanical professionals. Any repairs or modifications you do totally at YOUR OWN RISK. Use licensed professionals for all work to avoid possible serious injury or damage. Use  banks for purchases.  Have fun!

Copywrite & Trade Mark Registered GoodOldRV© ,GoodOldRVs©,©,©,GoodOldRV.Com©

© 2021   Created by Russell E Johnson.   Powered by

Badges  |  Report an Issue  |  Terms of Service