Hi Jim.
They say a picture is worth a thousand words.
From right to left Enya Sppedy 09, Thunder Tiger 09 and Enya 15-5
I have both of those engines as well as an Enya Speedy 09. The TT has a hole spacing of approx 1 3/16ths center to center and the Enya 15-5 has a spacing of approx 1 5/16ths. Case width on the TT is approx 7/8ths and the Enya 15 is 1 inch. The TT appears to be considerably lighter than the Enya but I don't have a scale to measure them. The Speedy 09 is almost identical to the TT
Hope this helps
Dan