work with your machine shop. you need to bore/hone/line-hone and deck the block and check bearings prior to buying parts
pick the appropriate cam K-kit. https://www.compcams.com/products/comp-camshafts/engine/305-350-c.i.-8-cylinder-o.e.-roller-(1987-1998)/usage/marine.html
this is the...
get more light under the drive and re-take the picture in post #11 with lots of light to eliminate any shadows. if that is a weld bead. you need a new gear box
volvo never made a 3.7 liter
do you mean 5.7 liter?
what props are on there now. unless you change how much power the motor produces or the drive gear ratio, pretty sure you cant jump between F3's and F5's
what kind of boat?
how much does it weigh?
what is the health of the motor?
compression numbers?
there is no difference between a 9.5hp and a 10hp that you can measure
I dont think you have a quadrant gear or pinion gear issue.
I think you have a gear box casting issue
looking at this picture, it looks like your clutch housing broke at one point in the boats life and someone welded it back together
the outdrive is 3 pcs. the two outer ones have a water pump separating them. check the upper gear box for water.
also, if it sat this long, get a new water pump assembly.
videos..... https://forums.iboats.com/threads/a-couple-of-new-videos.570843/
articles... https://forums.iboats.com/threads/must-have-technical-information-for-diyers-an-work-safe-search-version-of.335378/
as stated above, you smack the alignment tool up/down/left/right to center the bearing...
if the shims are too loose, the bearings spin and the gear box eats itself. if the shims are too tight, the bearings seize and the gearbox eats itself.
the folks at TC Marine (www.sterndrive.info) still sell parts. they may have a rebuild service.
