i have a 2001 htm ss24 with a 565ci (about 650hp) with 253 hrs on the outdrive. i want wilson to blue print the imco lower but sould i have them replace the gears and bearings too? how long do these things last? boat runs 97-98 on gps but not sure about getting the upper and lower rebuilt. input please!

hope to get 3-4 mph from the blue print of the imco lower?

With that much time on the drive I would definitely replace the bearings in the whole drive. The gears are another story, you're really not making that much power so if you're going easy on it on take-off they might still be good. Any good shop can let you know if you need to replace the gears upon inspection. You can even look at them yourself when they pull it apart, if the hard-facing is starting to peel than you need new ones.

According to MR.Gadgets, a good drive guy, gears from around that time hold up better than more current gears. So if the faces are not galling off, you may want to run them.