Original configuration of a 72 K20
 

Hey guys, just had a quick question. What would have been the standard differential type/gear ration configuration on a 72 K20? Are the 72's more or less desirable than other years? Not much of a 4x4 guy... :sumo:

Re: Original configuration of a 72 K20
 

44 front Eaton rear, could be a Dana 60, don't know why one over the other....ratios, just guessing but 3.73 up to 4.56s...

Re: Original configuration of a 72 K20
 

Also just guessing, 4.10 ratio may be the most common on a '72 K20. I personally prefer '71 or '72 over earlier trucks because they came with front disc brakes. Not a huge deal because obviously those could be upgraded on an earlier truck. Also, I think frames were different on '67s so replacement springs are harder to come by.

Re: Original configuration of a 72 K20
 

I believe the automatic K/20s got 4.10 and 4spds got 4.57s. Front axle was Dana44 and rear was HO52 (Corporate). GMCs came with Dana60 rears and were 4.11 automatic/4.56 4spd. I think 71 & 72s are equally most desirable due to having the most improved drivetrain

Re: Original configuration of a 72 K20
 

i just bought a rolling frame from a guy that he said had a eaton 72 rear which he said is one ton. any truth to this?

Re: Original configuration of a 72 K20
 

its a 4x4 so would that make it a k30?

Re: Original configuration of a 72 K20
 

I believe the Eatons were 1 ton rated

Re: Original configuration of a 72 K20
 

There were no K30s built in 1972. It may be a K20 frame with an HO52 differential, which is same as an HO72 except for brakes. There *might* be a difference in axles, but the pumpkins are the same. Some HO52s had the load bolt and some did not, while all HO72s had it.


Edit: IF it's a 2wd frame converted to 4x4..... I'm pretty sure C30 frames had larger (taller) c-channels than C/K10s or C/K20s, so you could measure & compare to a known frame.

Re: Original configuration of a 72 K20
 

Here is the powertrain chart.

Re: Original configuration of a 72 K20
 

No 30-series trucks were built with 127" wheel base. The only Fleetsides were Longhorns.

Re: Original configuration of a 72 K20
 

My original browsher says the ratios