how to align lower unit and tools needed after gimbal ring replacement
 

I have a 94 29ft scarab with twin 350 and i noticed before i put it away for winter it had a cracked gimbal ring. So i have ordered the jr marine kit, the gimbal ring, and the kit with gimbal ring, clamps, hoses, ect. but i have herd when i took it all off to replace it i need to align it when i put it back on and there is a tool. i looked on ebay and cant find it. so any help with this would b great. or any help on the whole job really. Also they are alpha one lower units

I believe all you need is the alignment tool for the outdrive.

The alignment tools are on ebay.
Do a search for
Engine Drive Alignment Bar Tool For Mercruiser P/N 91-805475A1 and 91-57797A3
$40 + postage
and
ALIGNMENT, GIMBAL BEARING, SEAL TOOLS FOR MERCRUISER
$70 + postage
Or go original for double the price.

There are many good tutorials on Youtube.com on how to do the removal, service and alignment.
You will also find some tutorials and advice at on the websites that sell "Mercruiser tools".
Do the " mercruiser tools" search in Google.
Go to the first 2 websites you find and you will discover ...

Sterndrive-Information
Change your Alpha Gear Lube
Change your Bravo Gear Lube
Why does my drive lube have white streaks?
Why does my drive lube have gray mush?
Replace Your Alpha-One Water Pump
Replace your Alpha Gen II Water Pump
Rebuild your Bravo Raw Water Pump

Troubleshoot & Replace your Alpha Shift Cable
Troubleshoot & Replace your Bravo Shift Cable

Replace your Alpha One Bellows & Gimbal Bearing
Replace your Alpha Gen II Bellows & Gimbal bearing
Replace your Bravo Bellows & Gimbal Bearing
Why does my drive "Growl" when I turn?
Water is leaking into my boat from the transom

Replacing your Trim Sender Switches
My Trim doesn't work but my Trailer Switch does
My Trim Gauge is Pegged

Rebuild your Alpha One Upper Driveshaft Housing Assembly
Rebuild your Alpha One Lower Gear Housing Assembly

Check your Engine Alignment
Check for Excessive Steering Play
Troubleshoot an Overheating Problem
Should I remove my thermostat?
Why do I overheat when going fast?
Troubleshoot a No-Crank Condition
Troubleshoot a No-Start Condition
My Engine Backfires and/or Surges and has Lack of Power
What is an Anti-Syphon Valve?
My Engine blows Steam from the Exhaust
Why do I hear a "clakity" sound while at idle?
Exhaust Manifolds...IMPORTANT Information
How do I Winterize my engine?

What is Galvanic Corrosion?
I have a Bravo III Galvanic Corrosion Problem
What is a Mercathode?
All about Zinc Anodes
How do I check my carburetor?
What carburetor do I have? A Rochester or a Mercarb?
I have water in my fuel
My fuel smells like varnish
My fuel is old
My engine has been sitting for several months without being run.

I have a Mercruiser 470, 485, 488, 190, 3.7L Engine
I have coolant dripping from the front of my engine
Can I install a regular Alternator instead of the Stator-Rotor?

Converting an OMC to a Mercruiser

Hope that helps.

Actually if you just replace the ring you do not have to check alignment, only if changing out the transom plate (inner or outer). But Merc recommends you check the alignment every 2 years at a minimum anyway so while you have the drive off you should do it.