Lower Unit on VZ175TLR vs. V150TLR

[COOPDUCK]

Hello
I have a question I'm hoping to get an expert opinion on. I live out in the PNW and have a jet sled with an '06 V150TLR with a pump on it. 80% of the year the pump is the best choice for the shallow rivers I run. The other 20% it would be great to have a prop for fuel efficiency, range, less cavitation,etc... I've decided I want to buy a lower unit and a bay kit extension to have the lower unit at the correct height relative to the hull.

I've been looking online for awhile for lower units, and have an great opportunity to buy a new lower unit that came off of an '06 VZ175TLR. The dates codes on the motors are two months apart. My outboard is the carbed Vmax 150. This lower unit came off an injected VZ175 HPDI. I printed off spec sheets on the two lower units, and of the approximately 100 components that make up the lower unit, there are only 5 different item numbers that the two lower units do not share in common. I will list the 5 items below if anyone is able to help with these. I will list the component from the VZ175 first, then the respective component from the my V150.

VZ175TLR
663-45376-00-00 guide, seal damper
61H-45551-00-00 Pinion (14T)
61H-45560-00-00 gear 1 (26T)
61H-45571-01-00 gear 2 (26T)
6G5-45384-02-00 nut

V150TLR
663-45376-00-94 guide, seal damper
6J9-45551-01-00 Pinion (14T)
6J9-45560-03-00 gear 1 (28T)
6J9-45571-02-00 gear 2 (28T)
6G5-45384-00-00 nut

My question is whether the lower unit off this motor will mesh right up and work appropriately with my outboard. My feeling is that all these components appear to me to be in the prop shaft assembly, and appear to be just very slightly different gearing specifically for the 175 power head. Whereas the lower unit for my 150 power head would have slightly different gearing. Knowing how much this lower unit will be on the outboard versus the pump, would I be doing any harm using this lower unit as is? Could the slightly different gearing be compensated for with prop selection? Bottom line, will this lower unit with these 5 slightly different parts work correctly with my outboard and not cause any problems? Any advice would be greatly appreciated. I don't want to pass up a great opportunity, but I also don't want to compromise my outboard.

[rodbolt17]

they will fit and can be propped around the ratio difference.
the VZ was a bass boat engine.
both the 175 and the 150 listed have 20" drive shafts.

[COOPDUCK]

they will fit and can be propped around the ratio difference.
the VZ was a bass boat engine.
both the 175 and the 150 listed have 20" drive shafts.

Rodbolt17
Thank you for the input on this, I purchased the lower unit in question earlier this week. So I just want to confirm one thing regarding propping around the ratio difference, per your post above. So from what I've been able to find, the published gear ratio on a VZ175 lower unit is 1.86. The lower unit that would have went on my V150 is 2. Does that sound correct? So if my mechanically challenged brain has this correct, the 175 lower unit I now own will turn my prop just slightly faster, thus more speed relative to RPM, when compared to that same RPM on the lower unit that was designed to go on my motor? Is that correct?

I've found some performance bulletins on Yamaha's site that show a V150 and a VZ175 on an 18 and 19 foot Xpress, which is about the most similar hull shape and dry weight to my boat as I'll find. They're running 13/23 and 14/23 props respectively on those two hulls. The difference is that all my prop use will be in moderate to severe chop, which the hull of my boat doesn't handle well at high speeds anyway. It is also a tiller steer. There is just no scenario I can think of where I will need or want speed anywhere in excess of 40, more likely even 30. Given that I don't need or want speed, and the lower unit I now have results in more speed, I'm thinking starting my prop search around that 13/14 inch diameter, but probably closer to a 17 or 19 pitch. Am I on the right track?

[rodbolt17]

sounds about right.
but it must be propped to turn about 5500 RPM with that days load.