He doesn't have the 4L60E, its the GM/Aisin automatic. Depending on which one it is, its either a THM-RMQ or the RMD Aisin. Either way, 4L30E is the best way to describe it.
Many of those seals are universal. You don't have to order the exact part, just get a seal that matches it and you'll be fine. Identify what part its sealing and go from there. Find a tranny shop, walk in with your seal, walk out with a new one for $1
