1978 24' differential

08-01-2024, 01:11 PM

I'm looking into switching from 4.56, to 3.73.
I've found references to GM 14 bolt and Dana 70.
Which diff came in these RVs?
Thanks

08-01-2024, 03:55 PM

Duane88

My 1971 Barth with a 1970 P30 Chassis has a dana70. Have not checked the gearing.

08-01-2024, 09:54 PM

billyt53

Why not just bolt on a Gear Vendors Under/Overdrive? It would give you the extra gear reduction you are looking for and add the versatility of gear splitting essentially giving you six usable gears. Your unit should have the park brakes in the rear brake drums so that would be the least expensive unit they have. I used and installed these units for decades.

Call them, they will send you the information.

If Rick Johnson answers tell him that I sent you!

Billy T

Billy & Helen Thibodeaux

Retired from Billy Thibodeaux's Premiere RV, Inc. Scott, LA 70583 I-10 Exit 97
The Farm is near Duson, LA I-10 Exit 92 then N 1 mile on right
Three Full 50 Amp RV Hookups !
billynhelen@me.com
Data Tag: 9404-3908-36XI-2C
1994 Sovereign 36' Widebody on Spartan IC (Mountain Master Lite) Chassis.
Powered by Cummins ISL9-450
Onan 8,000 Quiet Diesel Genset
Toad: 2018 Chevy Colorado ZR2 Diesel with M&G Car Brake

08-01-2024, 09:56 PM

billyt53

quote:
Originally posted by billyt53:
Why not just bolt on a Gear Vendors Under/Overdrive? It would give you the extra gear reduction you are looking for and add the versatility of gear splitting essentially giving you six usable gears. Engine RPM at highway speeds drop right at 600 RPM

Your unit should have the park brakes in the rear brake drums so that would be the least expensive unit they have. I used and installed these units for decades.

Call them, they will send you the information.

If Rick Johnson answers tell him that I sent you!

Billy T

08-01-2024, 10:02 PM

billyt53

quote:
Originally posted by billyt53:
Why not just bolt on a Gear Vendors Under/Overdrive? It would give you the extra gear reduction you are looking for and add the versatility of gear splitting essentially giving you six usable gears.

The overdrive ratio is .78 which brings the engine RPM about 600 RPM at highway speeds. The guys at the shop recently installed one on a ‘82 P30.

Your unit should have the park brakes in the rear brake drums so that would be the least expensive unit they have. I used and installed these units for decades.

Call them, they will send you the information.

If Rick Johnson answers tell him that I sent you!

Billy T

08-02-2024, 10:16 AM

Plugers

quote:
Originally posted by Duane88:
My 1971 Barth with a 1970 P30 Chassis has a dana70. Have not checked the gearing.

I'll have to look at it in person then. It's located a bit from me at the moment. As for the gearing, I just went by what the Barth brochures, and a P30/32 chassis PDF listed for the 159" WB chassis.
Thanks.

08-02-2024, 10:18 AM

Plugers

quote:
Originally posted by billyt53:
Why not just bolt on a Gear Vendors Under/Overdrive? It would give you the extra gear reduction you are looking for and add the versatility of gear splitting essentially giving you six usable gears. Your unit should have the park brakes in the rear brake drums so that would be the least expensive unit they have. I used and installed these units for decades.

Call them, they will send you the information.

If Rick Johnson answers tell him that I sent you!

Billy T

Thanks, I'll look into it.
I'm also considering a Vortec 8.1 / Allison 6 speed swap. I wouldn't mind the fuel injection, But I haven't done a computerized engine/trans swap yet.