The bars are the same size.
Try raising the rear mount with washers until the plate is centered and flush with the bellhousing. I have that same setup.
As you raise the rear of the motor you will have to raise the front mounts also to get the alignment tool to line up.
Years ago I was blowing a coupling at will every weekend. My tool went in and out like nothing. I even took it to a so called MERC. expert. charged me $100 and I blew the coupling that weekend.
I finally took everything apart and took a lot of time looking at everything. I finally figured out that my rear mounts had sagged and because the gimbal bearing pivots I would lower the front mounts and the tool would line up. BUT what was happening was the input shaft was at an angle to the input yoke on the drive. This meant that the two shafts at each end of the U joint were not on the same plane. ( I am not talking angle but plane) If they are not on the same plane this binds the U joint and causes side loading of the U joint and that side load gets transferred to the coupler. I had the plate made at a local machine shop and I use it every time. I was at 500+ HP before when I was blowing them. I am now at 800+ HP without any problems.

After I had the problem with the rear mount I started shimming my rear mounts so they can't ever move. I install washers and shims to set the height and then use a shorter bolt with very large washers on top to stop any up and down motion. The Daytona also has solid front mounts.

Tinkerer i will try the washers. It sounds u ran into the exact problem. The gimbal bearing pivots to keep aligning as i drop it on the front. It must have been tight because it was not even from side to side. Im sure thats why with the porta power on the crank it goes in/out with 2 fingers. This is not a performance boat by any means but i blew the orig coupler in 150 hours. I bought the boat used with only 20 hrs on it. The tool is definetely fully going into the coupler and is the correct diameter. I have a merc brand tool and aftermarket. The merc tool is .003 larger than the aftermarket tool in the gimbal bearing area and fits nice. I have a spare coupler i keep on the shelf and it slides in there perfectly as it should.

Ok .100 washers are in. The plate was over 1/8 out and now its only .065. I didnt measure the od of the washer. Does anyone know the size? Should i add or make a single .165 shim? Tinkerer how far out was ur plate that caused you to eat couplers? I was cheating by lifting each side with a porta power. Not sure i have vertical clearance to add much more. Really dont want to pull engine cover off...lol.

thanks for the help!

OD of mine is .872..assume .875 nominal. .104 thick (saved them for another day)...looks like you are making progress!

After installing the .100 washers i was able to close the gap by raising the front. Shes nice and flush and bar slides out with 2 fingers! I wonder what the deal was from the factory? Because i even replaced the rear mounts about a month ago so they were not sagging. Transom has no signs of rot and it stripped the first coupler at 4 years old. Was the inner transom plate just installed wrong? Gotta throw the drive on in the morning and go for a test run!

Everyone who helped me, thank you very much!

Sorry I don't remember how much it was off. It was about 30 years ago.
Years ago I had an on line fight over this same subject with the then MERC. guru on this site. He told me I didn't know what I was talking about. And I told him that about this subject I guess I knew more than him. To say that I got flamed was an understatement.
I found that with most boats IF the alignment tool is parallel with the running surface it works.
I spent a lot of hours figuring out what was wrong that was causing me to blow couplers.
I have NEVER blown one again.
I just know for a fact that if the rear mounts get out of place high or low you can raise or lower the front of the engine to get the alignment tool to say the engine is perfect but it isn't and the more HP you have the sooner the coupling will blow due to side loading.
The center line of the input shaft and the center line of the upper out drive shaft must be in the same plane. They can be angled because of trim or turning but this does not move the center line when the drive is at the neutral setting.
When they are not in the same plane the U joint is crabbed sideways ( up and down actually ) This puts a side load on the coupler that it is not supposed to see.
I literally could blow a coupler in less than 5 hours run time.
Sounds like you are getting it fixed.
I don't understand why the rear mounts have rubber inserts at all. I understand vibration issues but I have never felt any and I have been locking down my rear mounts for at least 30 years.

Well test drove it today. Small vibration from about 800-1200 rpm. Can feel it with my hand on top of windshield. I think i can do better as far as alignment. Getting it perfect with everything tightened up was just a pain in the ass. My merc bar i could just barely pull it out using my middle and pointer finger. So i think i can do better. Ill try again this week. What i found interesting is for the hell of it i checked the angle of the engine and its 13.0 degrees!https://cimg7.ibsrv.net/gimg/www.off...ee2686e3f9.jpg

best tool for any sterndrive alignment is the ITS alignment tool by far. It will tell you coming thru the gimbal bearing how far off your not centered,

The next thing you want to do is by hand at the crank turn the engine over every 90 degrees and keep checking the ITS tool in its position to make sure it never changes, It is best to have 2 people one eying up the rotation of the ITS alignment tool and the other hand rotating the engine every 90 degree turn stop at each 90 rotation. If that position changes at every 90 degrees of rotation or even at 180 of rotation then you have a warped coupler or bent flywheel or the coupler or the flywheel or both are NOT mounted perfectly flush.

Sorry I did get your PM but I am really busy and can not answer every single PM s . I try like hell to answer everyone but that does not pay my bills. Sorry about that one

This is a good tool to have but there is an issue with using it that will fool many for checking perfect alignment,

https://drive.google.com/file/d/0B4y...Z5a0Nhek0/view

The issue is the gimbal ring / bell housing will drop cause the the nut on top of the swivel shaft will loosen over time. This drops the bell housing down - with that said the tool / plate here in the pics is worthless unless you tighten / bring back the nut to spec clearance by tightening it. But that requires removal of the transom assembly to do so.

My buddy Mark and I just talked about this exactly. So Mark if you see this haha