I can tell you I had 4.10 with the SM465 and 33s and loved the setup. I now have 4.56 with 33s and it's screaming metal now for sure. But going to 4.10 is the wrong side of the carrier break and you will be into it for some money. As long as you are spending the bucks, might be better to go a bit taller gears 3.73 than 4.10 and adjust down with tires. And I do think the 4.56 gears are more noisy, they seem to bring out the harmonics in everything. If you are touching the transmission I would go automatic. What more could you want for compound reduction and overdrive? I feel like you have the best manual truck transmission you can get. And of course it all depends... on... What you use the truck for... your skill level for conversions.... your wallet depth... and level of PATIENCE!
