I'm guessing that you have a 52" Lazer Z HP, and the Ultra Vac is from a 48" Lazer Z HP...if either of these assumptions are incorrect, (the 52" is a Lazer Z, or the ultra Vac is from a new generation 48" Lazer Z) then there's absolutely no matching up, literally nothing on the unit would cross over.
Even if they are both Lazer Z HPs, unfortunately the 52" has a different blower assembly than the 44" & 48" units have. I'm not going to say that you can't make it work, but it won't be easy at all, and in the end you may have something that you'll never get a belt to live on. On top of the blower assembly being different, the tubes and the double pulley to drive the blower assembly are also different...along with obviously the belt and belt shield.
The rear assembly may very well work fine, but you're probably looking at in excess of $1000 worth of parts to change everything else.
