I picked up a couple more Sherman kits to see if I could mix and match them to get the right sharp-nosed transmission housing for the Hybrid (from the M4A2 76mm kit). I now have all the Rubicon Shermans! I have to say, the M4 is pretty nice as well, so I decided to have a Ic and a Ic Hybrid (different types often appeared in the same unit). The Ic will have the rounded transmission housing, which seems to be accurate.
I found that the sharp nosed transmission housing isn't a perfect fit; if you insert the strip of retaining bolts (SF08), the hull doesn't sit level. I'll leave it off and cover the gap with stowage.
I started another thread on the Fireflies.