this is another great book and it covers basically your engine in thoseyears
the 5.5 and 7.5 are very similar and the general upkeep info incl ingnition carburation gear case etc..are all well explained.
make certain you check the GC oil for water intrusion. ...some folks just drain/refill mid season for small leaks .... the other option is a GC reseal.. a challenge the first time around but help available here and on the AOMCI ask a member we site forum where oldys are the main focus . great resource fo folks who sold- repaired or made those engines !
www.aomci.org