I couldn't find a shifter boot for my G360 trans. Nobody including the trans rebuilder had them. I used a Dorman # 614-001 CV boot kit from AutoZone. I cut off the bottom ring and used the clamp I had on the old boot and a Tie-Wrap on the top end around the shifter. I pushed it down as far as I could below the raised ring on the shifter. It isn't perfect but it keeps the oil in.

Edwin

 

I used one from a G56, fit perfectly.

It doesnt use a clamp on the G56, but you can still install the original clamp from your G360, just make sure not to over tighten it.