There are 2 spacing and they don’t match when VVT was added with the ‘09-‘10 5.7 and 6.1 spacing matching the ‘08 down non-VVT spacing. So an ‘09 water pump might work but no idea if it will bolt on as the timing chain cover is different and I don’t know what changed.
I know the oil pump was pushed out due to VVT so the TC cover had to get deeper in that area but no idea what it did at the water pump area. If I had to guess, the water pump got pushed out as well and the swap won’t work, but not sure.
You would have to buy a water pump and try it though. My gut says the water pump won’t bolt onto the ‘08 TC cover, but just a guess.
I wonder if the TC cover could be swapped at the same time though. If the ‘09 TC cover and water pump were used with the ‘08 crank pulley pretty sure everything would line up. I know the alternator and PS pump cross over so makes sense it would work. The missing data is if there is something different in the bolt patterns.