Can't speak for the S-trucks(that's a pretty light duty rear end anyway) but my '84 K10 has 2.73 axle ratios in it so I imagine that 3:08 was available also. When the K10 finally gets too rusty to be safe I think I will have the rear axle rebuilt(190K miles on it now) and put it in my '37. I have a late fifties corporate HO33 rear axle with Patrick's 3:38 ring and pinion in it now, but running a 235 with smallish tires I find the gearing still too low without an overdrive(I use a SM 420 tranny also). The 2:73 will probably be just right. Shouldn't be too hard to find a 3:08 corporate 10 bolt or Dana 44 from a K10 or Blazer in the junkyards.
