CM 871 Timing

[2dlb]

Hi Guys
I wonder if someone could get me straightened out on turbos. I went to our turbo shop yesterday thinking im looking for a He551Ve to replace the one i have on this 871 with a CPL of 2733 set at 485hp. Insite pt # is 5350895 if i got it right which matches with the tag on the turbo. Kit# 4309077RX ,Assy# 3774602. So.. In a discussion with buddy (and there may be a slight language barrier), I get that the turbo i have is an He561Ve, ok so back in the fall i posted about changing turbos on another 871 and it wouldn't preform a regen so i went back and got my old one and put it on and everything worked,So yesterday while im trying to figure out whats the difference i notice that there are 2 different covers for the turbine as well there are 2 different shaft sizes am i correct that a 561 can have a 72mmX12 small shaft, as well a 72x12 large shaft or a 77mmx12 which i would assume would be for the higher HP. If this is correct then last fall the first turbo i brought home and installed and the truck wouldn't regen must have been the 77x12. I remember reading sometime ago that Rawze said a larger turbo would work but at the expense of lag and fuel. This thing was demandated and im trying to get it back to good, Theres not a lot of info available for a breakdown on turbos, or at least not that i can find.
Thanks