There is no difference in the stub shaft length from DRW to SRW. The only difference is the bearing hub itself.
The dia. of a SRW hub on the outboard end (at the locking hub) is 4 1/4". It has a slight taper, the dia on the hub at the outboard surface of the rotor is 4 1/2".
This applies to Chevy 60's only, Dodge bearing hubs are different (don't know about stub length) and all of the Ford stuff is shorter (bearing hub, axle & spindle).
Hope this helps.