1978 Sleekcraft Diplomat, which outdrive do I need?
+ Reply to Thread
Results 1 to 6 of 6

Thread:
1978 Sleekcraft Diplomat, which outdrive do I need?

  1. #1
    Junior Member
    Join Date
    Oct 2012
    Posts
    4

    Default 1978 Sleekcraft Diplomat, which outdrive do I need?

    So I'm trying to find an outdrive for a 1978 Sleekcraft Diplomat. The boat originally had a Mercruiser 350 and an outdrive, but I've having trouble finding the information on which drive I need (boat came without the engine or drive, have an engine, need a drive). It's a 1978, so its not an Alpha, but I can't figure out if its a Mercruiser MC-1, Mercruiser R, or an MR (Pre Alpha). I've also seen different gear ratio's and so on and so forth. This boat is going to be ran for the 2013 season with a 350 and a replacement drive, and then be parked for new upholstery and carpet and a 454 and Bravo One swap, but for now I just need to get her running good for the season. If anyone has any idea what drive I need, that would be fantastic. I'm told all the transom assemblies are interchangeable, so now I just need to worry about getting the right drive. Thanks guys!

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    It's what we do BDMarine's Avatar
    Join Date
    Dec 2007
    Location
    El Monte
    Posts
    723

    Default

    The R/MR/Alpha One were all built between 1983 and 1990. The 1978 upper (driveshaft housing) parts all supersede to the same part numbers as the Alpha One. (Not the Gen II, post 1990)
    Assuming your boat has the 1978 transom assembly installed, just not the drive, you can get any Alpha One R/MR/Alpha One drive and it will work. (Not the Gen II)
    Just make sure it has the correct gear ratio for your engine's HP.
    http://www.performanceboats.com//signaturepics/sigpic837_1.gif
    B & D Marine Performance
    El Monte, Ca.

  4. #3
    Junior Member
    Join Date
    Apr 2012
    Posts
    19

    Default

    If you have nothing and plan on a bravo later why not just get a bravo now?

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Junior Member
    Join Date
    Oct 2012
    Posts
    4

    Default

    Quote Originally Posted by BDMarine View Post
    The R/MR/Alpha One were all built between 1983 and 1990. The 1978 upper (driveshaft housing) parts all supersede to the same part numbers as the Alpha One. (Not the Gen II, post 1990)
    Assuming your boat has the 1978 transom assembly installed, just not the drive, you can get any Alpha One R/MR/Alpha One drive and it will work. (Not the Gen II)
    Just make sure it has the correct gear ratio for your engine's HP.
    Wow awesome, thank you so much for the information! The way I'm getting the boat, it has the transom plates and the coupler, but no motor, no upper or lower drive. I have a Mercruiser 350 lined up from another friends boat with a cracked hull (his drives already in his other boat) and I had a few tips on some drives. I just needed to find out what I need. Thanks again! My only real question left is how do you measure what splines you need for your engine? If I go with the 350, what splines should I need? Alternatively, how about a 454 (I did plan to upgrade) and the Alpha one or even a Bravo? I suppose I'll start Google searching again.

    Quote Originally Posted by professor_speed View Post
    If you have nothing and plan on a bravo later why not just get a bravo now?
    I appreciate the opinion. I was planning on going with an Alpha because I can get my hands on one in good running condition with low hours for a good 200-400, but the only line I've gotten on a bravo was 1500 for everything in unknown condition, 800 for just the transom plates, and 1000 for just the lower. The Alpha seemed like a better starting point. However, now that I stop to consider the choices at my disposal, this boat what touch the water until April-May of next year, giving me ample time to put the cash into a bravo. I think I will do some thinking over the next couple days. To upgrade to a bravo its just drilling two new holes, shouldn't be that big of a deal. Thanks for your input, it was much appreciated.

  7. #5
    It's what we do BDMarine's Avatar
    Join Date
    Dec 2007
    Location
    El Monte
    Posts
    723

    Default

    Quote Originally Posted by DirtyGirl045 View Post
    Wow awesome, thank you so much for the information! The way I'm getting the boat, it has the transom plates and the coupler, but no motor, no upper or lower drive. I have a Mercruiser 350 lined up from another friends boat with a cracked hull (his drives already in his other boat) and I had a few tips on some drives. I just needed to find out what I need. Thanks again! My only real question left is how do you measure what splines you need for your engine? If I go with the 350, what splines should I need? Alternatively, how about a 454 (I did plan to upgrade) and the Alpha one or even a Bravo? I suppose I'll start Google searching again.
    You're welcome!

    All Mercruiser splines are the same. However, there are many different couplers depending on the year and type of drive. I would not recommend a big block with an alpha drive. The drive does not last well with the torque of a big block.
    Bravo One's take a different transom assembly.
    http://www.performanceboats.com//signaturepics/sigpic837_1.gif
    B & D Marine Performance
    El Monte, Ca.

  8. #6
    Bah... HST4ME's Avatar
    Join Date
    Dec 2008
    Location
    Michigan
    Posts
    2,546

    Default

    go to sei, buy a brand new cheap outdrive with a 3 year warranty, go boating. 1.50 ratio btw.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95