Been looking for mobil 423 and can't seem to find it anywhere. Is there any other type I can use.

Merc Hi Perf Gear Lube. Blue look'n stuff.

Mercruiser told me direct to use a 10 weight tractor fluid and they recommend mobil 423 for the tranny not the lower unit. Are you getting those to confused or are you saying I can put the gear oil in the tranny and in the outdrive too?

Merc. Hi-Performance Gear Lube in the drive and Type F transmission fluid in the tranny. Or... Amsoil has some good products that I switched over to.

This is what you want for the tranny.
http://www.amsoil.com/storefront/art.aspx

This for the drives.
http://www.amsoil.com/storefront/agm.aspx

If you need some, shoot me a PM. I can hook up the price.

Actually, after some quick research, it looks like they're recommending a Tractor Hydraulic/Transmission oil. It looks as if Mobil has replaced their 423 with a 424 fluid. Here is the AMSOIL equivalent...
http://www.amsoil.com/storefront/ath.aspx

Yep. Was confused sence all you said was TRS fluid. If you have a Borg-Warner manual says type F. If you have a Merc Trans ll you use Dex/Merc. These are availiable at any auto parts store.