[Yukon Jack]

My GM restoration pack shows for the 2wd K5 that 3.73 was standard for the 250 six regardless of transmission and standard with the 307 V8 with a three speed.

3.07's were standard for the 307 V8 and 4 speed manual or auto, along with any 350 V8 combo.

4.11's were optional for all and if it had the 3.73's then 3.07 was an option and if it had 3.07's then 3.73's were also optional.

For the 4wd K5 3.73's were standard with all engines except for the 350 V8 which it shows only got 3.07's.

For whatever reason it doesn't show any optional gear ratios for the 4wd K5's.