The K L is left side. The other one says K R
My '85 Suburban has those tar/felt inner splash shields.
Yep, not to identify the frame, to identify which side the mud shields go on lol. I've heard of the material referred to as mastic, but I'm not sure that is correct. Personally I feel its slightly stronger than roofing felt. Unfortunate, as over time they tend to tear, as far as I can tell mainly due to turbulence from driving at speed.


I don't know if it's a squarebody or something else, but I swear I've seen left and right stamped into frame rails before too. I know part numbers, but that's a bit different.
I'm going to try to reinforce mine. To cheap to buy new ones. LolYep, not to identify the frame, to identify which side the mud shields go on lol. I've heard of the material referred to as mastic, but I'm not sure that is correct. Personally I feel its slightly stronger than roofing felt. Unfortunate, as over time they tend to tear, as far as I can tell mainly due to turbulence from driving at speed.