First, welcome aboard
Owners manuals generally do not exist for boats.
Get the factory service manual for the motor/drive
Tallahatchie boats operated from 1972-1986 in Wisconsin. A boat that old will have structural issues
A 1982 should be full mechanical shift. Electric shift went away in 1977
The iron duke is a 151 cubic inch Pontiac motor. Shares nothing but valve cover bolts with the Chevrolet 153 cubic inch used in boats
Barr is the OEM casting house for Edelbrock, Volvo Penta, Mercruiser and others.
GLM stands for Good Luck Marine.
Osco sold the casting business to Sierra. Name only, none of the equipment or talent
With that stated. OEM or Barr
I have a few cut-up plug sockets (similar to an O2 socket)
Also, unthread the wire spud. It gives you wrench clearance. Then thread the wire spud back on