I installed the Vortek piston seal in my old RWS 45 (Diana) about 6 months ago. It had the original leather seal which is held on the end of the piston with large permanent pin/rivet. That has to be cut off and the end of the piston drilled and blind tapped to accept the seal kit. I did this and it was successful but due to the construction of the end of the piston, it may not be structurally sound in the long term. The Vortek kit is really meant for other models that have a screwed on seal. They offer a disclaimer that modification is necessary on a model 45 to make the kit work but that's an understatement and IMO probably shouldn't be done. When you take down the gun, pay special attention when you remove the pins from the trigger unit. They engage a flat u-shaped spring (like a wide bobby pin) that provides tension and a detent for the safety. You'll want to see it's proper position. When I disassembled mine that spring fell out before I could see how it installed and it took a bit of head scratching to figure out where it went when I put it back together.