Need help with VDO tach calibration, please.

[YerDugliness]

Hi, folks. I have a question regarding calibration for a VDO tach. IIRC it is the one with the three switches on the back, but I am not near the car right now to check.

I did a forum search and came up with only this one thread, but it doesn't help as I think mine is different from the tach discussed here:

tach calibration

I have done many internet searches for this issue and cannot NOW find a diagram to show how the three switches should be configured for this old VDO tach (verbal history indicates the car was assembled in 1994). I do remember doing a search when I bought the car 4 years ago, found diagrams of the back of the tach with recommended positions for the three switches, but now everything seems to be dedicated to electronic methods...diodes or resistors, that sort of thing...and has anyone seen the prices repair/calibration shops charge for this service? Highway robbery, if you ask me...in excess of $100 to switch three sliders? Not in this life.....

If anyone has a URL link to the positioning of the three switches (as I recall each of the switches had only two positions: up and down), or perhaps has a diagram they could share on this thread, I sure would appreciate it. As it is now, my box-stock 5.0HO engine seems to be running over 4K at highway speeds (65 MPH) and likes to be shifted at around 8K-9K.....see what I mean????

TIA for whatever help you can give this ol' cowboy!

Cheers!

Dugly