I have a frog and brat, you may order the frog shell as parts from Waigo, but you need to have two special pins to hold the two rear sides of the frog shell and lower to different position of the front stand, due to the shell stands are different!!
Hey guys. Just want to share some "old man" experience. If I remembered correctly, there was no diffential gear in the 1st generation Brat but in the 1st gen. Frog. Acturally, Frog was an enhanced version of Brat and Lancia Delta as well.