Speedometer off

[Red Rex]

My speedometer reads 5 mph faster than my gps.

208c transfer case original equipment
Th350 transmission replaced 700r4
3.08 gears original equipment
30 inch tires

I have changed the speedometer with a junkyard part

No adapter on the transfer case. It has a black plastic gear in the housing.

How can I tell what gear in the housing I need and where might I get it or do I need to change the speedometer?

 

[C10MixMaster]

My speedometer reads 5 mph faster than my gps.

208c transfer case original equipment
Th350 transmission replaced 700r4
3.08 gears original equipment
30 inch tires

I have changed the speedometer with a junkyard part

No adapter on the transfer case. It has a black plastic gear in the housing.

How can I tell what gear in the housing I need and where might I get it or do I need to change the speedometer?

You dont need to change the speedometer. You need to change the gears.
here's a link to a similar post that might help https://www.gmsquarebody.com/threads/np208-speedo-driven-gear-needed.20778/

 

[Red Rex]

Appreciate the information and post!

 

[LateOnTheBrakes]

What gears did you end up going with? My truck is a mix of 4.3L V6 and CUCV. I don't know which of the two my transfer case came out of. What I do know is the V6 should have come with 3.73 rear gears and my truck has 3.08 in the back. My speedometer reads about 35mph when I'm going over 50mph.