T5 swap in '47 1/2 ton (jailbar)

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Feb 6, 2026 | 03:16 PM

tlktchr

Thread Starter

Trailering

Joined: Jan 2026

Posts: 20

Likes: 4

From: Auburn GA

T5 swap in '47 1/2 ton (jailbar)

Has anyone here made this swap? I have just about everything figured out except for the speedo gear. Does anyone know which gear I need? T5 from a '91 S10, mated to a 239 flathead. Everything else is bone stock.

Feb 7, 2026 | 10:00 AM

51504BAT

More Turbo

Joined: Mar 2010

Posts: 701

Likes: 76

From: SoCal - Redlands

Hopefully GB Sisson will see this and chime in. Or you can ask over on the Ford Barn, He's on there more often. He installed a T5 behind a Merc in his homemade woodie wagon. He is pretty much all things jailbar.

Feb 13, 2026 | 08:46 AM

tinman52

Welder User

Joined: Feb 2009

Posts: 5,269

Likes: 49

From: northwest MT

The '91 T5 uses an electric signal type speedometer. To use a cable driven speedo you must switch to the early T5 tailshaft/housing, or use a converter box