TH400 speedometer gears?

[zieg85]

I can't seem to find a source you can go to for determining the correct gear set needed to have the speedometer read right.

Currently I need to change out my TH400 in my C30 and I am changing the rear end while I am at it.

I will end up with a 3.21 and LT265/75R16 tires.  I know I may have to adjust the driven gear once I see how it is but while the transmission is on the bench I would like to know what drive gear is needed.

Thanks in advance

[bd]

Have you seen the attached page from the 85 parts book?

[zieg85]

Awesome Rich, THANK YOU!!!

[Irish_Alley]

where did you get that from rich? maybe have a full set for the tech section?

[bd]

It's 1 of ~77 pages in the 4.450 parts group for 1985 - 1990 C/K/R/V.  Every year is represented by its own unique set of charts organized by transmission.