Question for those with a 203/ 205 doubler (fabrication question)

[CoFarmer]

I'm about halfway though my 465 and doubler build. Right now I'm looking at making an adapter between the 203 and 205. My question is; why do most of the "pros" I.e ORD and Northwest convert all the 205's to a female input? Currently my 205 has a 10 spline male input shaft. I'm thinking of re-splining the current over-sized shaft out of the 203. It would become a shorter 10 spline and then just reusing the 10 spline collar that was connecting the 465 and 205 before. I.e ,male to male like the factory 465 to 205 setup. If these aftermarket companies convert to female to save length I might understand, however, if it's for strength I'm having a hard time seeing it. Can doubling my gear ratio really put that much more stress on the collar? GM put this 465/205 setup on some pretty good size one ton trucks and light duty grain trucks in the 70's

Long story short, I can make an adapter and re-spline on our mill for free-ish..... Or I can buy the conversation kit and adapter kit for $1k. Thoughts advice?
Thanks

 

[zebrabeefj40]

I'd go the DIY route first. If it works you're done: if it fails you are out your time and $1k for the kit. The only issue I see is that 10 splines will likely wear faster than a higher spline count shaft. The higher spline count shaft is also likely larger than the 10 spline shaft. Will it matter in an FJ40? I have no idea. But I do know that the 16 spline output shaft of a stock H42 trans does wear out in stock FJ40's...

Good luck!
Nick