Inboard or tournament style ski boats have been around since the 50's. My experience covers the mid 70's and up boats. Prior to the 70's there were many cottage type companies building marine power trains and they didn't keep to many records. There were also many boat builders that grabbed what ever parts they could find at the time of build.
From 1971 and on the Ford Windsor 351ci and 302ci were the base engine of choice. This base engine was then "Marinized" to make it water ready. Also used but in smaller numbers were GM 305ci, 350ci and 454ci base engines. In 1994 Indmar went to all GM based engines, PCM used Ford's primarily until 2001 when supply ended. You need to know who made your engine water ready and is it Ford or GM based. I will list some in a chronological order.
1971 - 1975 "Waukesha" later bought by PCM
1975 current "PCM" Pleasurecraft Marine
1978 aprox "Escort" later bought by PCM
1979 aprox "Commander" out of business mid 80's
1975 aprox "OMC" not many used after 1980
1986 current "Indmar"
Beginning of time Mercruiser on and off
Transmissions were usually "Velvet Drive" with 1:1 or 1.52:1 ratios, your prop size will tell you what ratio 14X18 = 1.52:1, 13X13 = 1:1. In 1989 PCM also started producing their own transmissions 1.23:1 ratio and 1:1. You can also look at the ID tag located by the dipstick for the model number and ratio. Around 1996 Indmar started using Hurth transmissions.
