I just bought this muncie 4 speed today, I'm not sure about what gear ratios it has. I believe it is a m-20 from what i've been seeing. The main case numbers are 3885010. Rear tail is 3846429. Patent number is 3088336. The front shaft is 10 spline with 2 rings in the spline. Any good websites for this kinda stuff? Thanks for any info.