How does the Sterling rearend in a SRW 88 F350 compare to a Dana 70 rearend.
Either being 35X ratio with an automatic and a FI 460.

 

There pretty close, especially from 93 to 98. Read this,

Ford 10.25 & 10.50-Inch Axle Tips - Sterling 10.25 Upgrades - Four Wheeler Magazine

DANA 70
Almost identical in appearance to a Dana 60, the Dana 70 is standard in heavy Dodge pickups and GM duallies. The large 10.54-inch ring gear diameter will tolerate much torque, and is suitable for diesel power and/or big tires.
FORD 10.25-INCH
Ford's biggest axle comes with semi-floating shafts in 1983-and-newer F-250s, and as a full-floater in F-250HDs and F-350s. Applications are similar to the big GM 14-bolt and the Dana 70.

 

sterling 10.25 , dana 70 , GM 14 bolt are all in the same class !!