Well the bike was built in 91 and it measures 135mmDidn't know 135mm were thing in 1991?
My Klein is classed as a touring bike so that would make senseRoad tends to be 130, MTB and heavy touring is 135 to allow for an extra 5mm on the nearside and reduce the wheel dish
If you find 135ulregra, someone has added an aftermarket longer axle and a spacer