also how do I cover up the original two lag bolts hols in the stringers? whats the best way to fill those holes up in the stringers?

use some west system from boat usthat stuff is amazing.my 2cents

Because your mounts bolted to the top of the stringers you won't be able to use offshore mounts since they would put the mounts inside where yours are now mounted.
What you could do is have a inverted U made that slips over your stringers and your mount bolts to the top of the U.
Then you bolt through the stringer to give them the support.
Fill the old holes.

tinkerer I don't think I understand what your saying i guess? I can't use offshore mounts because mine are mounted on top of the stringers now? I guess my question is why can't I just take the lag bolts which go on top of the stringers and take them out, fill that hole up with resin or something and just buy the things I need to use offshore mounts? There would be no more lag bolts now or stock pos motor mounts

The inverted U is the cheapest,quickest fix .....those are not Offshore mounts ..... these are offshore mounts .....
I would clean the holes where the lag bolts were and fill with Thickened West system epoxy ..... I thnk you can get it in a tube now .....the inverted U's need to be long enogh so you are Thru bolting thru Virgin area ....m

You should measure between stringers to see if the stock offshore plate will fit between the stringers. That is what he is talking about. If you have to get custom made offshore mount it will be expensive.

Congrats, you have rotten stringers!!! Been there done that. Depending on the severity of stringer rot will determine your best fix. If the rot is significant to the point where the whole stringer is in question, I would suggest the u channel but get a longer one say 2 feet and 1/4 to maybe 3/8 thickness. Then multiple through bolts to take up the total clamping load. If you use a short u channel, you will collapse the rotten stringer under clamping loads, decent clamping load required to keep the 1100 lb motor where it belongs. If it is localized rot, decap the area, dig out the rot to find good wood, refill the void with a mixture of west systems epoxy and chopped glass. The reglass the area you removed on the top, drill the necessary pilot hold, the reinstall the mount and lag bolt. All best done with the engine removed. Sound painful? It is. But what is worse if your mount fails, binding up your output shaft with the universal bearing, subsequent loss of the bearing and then potential sinkage if your outdrive boot tears under the excitement. Also, you won't be able to sell the boat for good used parts value since no new owner wants to deal with stringer rot. Good luck and make it safe/reliable.

I already checked the stringers, stringers are fine it's just one one side whoever had the boat before me somehow threaded out those lag bolts, looks like they didn't know what they were doing! That's the very first thing I did when I took the engine out I inspected the stringers very carefully and thankfully they checked out good!

Ok, then your repair sounds easier with no engine removal required! Simple drill a pilot hole deeper, brush the inside of the hole with some epoxy, and bolt down a longer lag bolt that is coated with wax, install the lag bolt just before epoxy sets. Lag bolt length should be more than twice the length you have now. Why epoxy? To prevent addition rot. Why the wax on the lag bolt threads? So you can remove the bolt later. Why let the epoxy begin to set before installing bolt? You won't initiate crack lines associated with hardened epoxy and makes for an easier install/bolt torqueing. To get longer lag bolts of same diameter, try ACE hardware or Florida Bolt...they both carry sst lag bolts.

If the motor was moving around at all, check your coupler over while its out of the boat.... an ounce of prevention...