need help to determine what out drive i have

[snydes65coupe]

i just bought a 1984 24 foot thundercraft and the upper gear set is lock up. need help to find ratio and what outdrive i can use,
can't find any number on casting, its a 305 v8 228hp, sorry new dont know if more info is needed and pic is not that great, will post better pic later

 

[Deano39]

Re: need help to determine what out drive i have

Im no expert but it looks alot like the one on my 76 imperial. Its an Alpha one Gen one..

 

[nola mike]

Re: need help to determine what out drive i have

Not an alpha one. Looks like an MC-1.

 

[Eric 3.7LX Alpha 1]

Re: need help to determine what out drive i have

It does look like a MC-1, lift ring on top cap, and rounded corners on the excavation plate. The link from the "sticky" says "1-R" for that year.

Your ratio will/should be 1.50:1. New models have 1.47:1 which is close enough.

There could very well be metal now also in the lower and you may want to find a whole drive rather than just the upper half.

If you go SEI it will be a model 106.
http://www.sterndrive.cc/mm5/merchant.mvc?Screen=CTGY&Category_Code=MercruiserAlpha

Just keep in mind the universal joint splined yoke. There are 2-different lengths, the older models were shorter. I don't know what year they changed. Just measure yours

Almost any model up to and including Alpha One will work as long as the ratio is correct. Gen 2 will not work.

 

[Bondo]

Re: need help to determine what out drive i have

Just keep in mind the universal joint splined yoke. There are 2-different lengths, the older models were shorter. I don't know what year they changed. Just measure yours

Ayuh,.... It's not a Year thing, it's a Motor thing,...

Only the In-line Chevies used the shorter shaft,...