What is available?

Alldata list:

32/38 x 3.29 = 3.91
32/38 x 3.05 = 3.63
35/35 x 3.29 = 3.29
35/35 x 3.05 = 3.05

But Dacco also lists a 37 and 38 tooth drive sprocket as well as a 37 tooth driven for a 4t40e in a 4t45e document:

http://www.daccoinc.com/pdfs/catalogs/4T40E_4T45E.pdf
(Part 705, 706 in the diagram.)

So is that to say that 4t40 sprockets fit 4t45's? If so then would that mean other ratios are possible in the 4t45's? For instance, I would love a 38/35 x 3.05 = 2.81 final ratio.

 

No idea, but what are you using it in?

 

Rock buggy