Have two TRS's , 1.5 : 1.0 ratio, from 39 Scarab. The serial number , by the merc book, is stampedon the drive shaft housing directly below the merc decal. Is it possibially under layers of paint. Is there an easy way to id the drives? The units are 15 spline prop shafts. Does any one know what is a TRS cylcone? i Are they the speed master club foot. ? Were the TRS standard model from about 1973 up to 1990'send of production. I was told by merc people that TRS was better than Bravo, but suffered more drag.

You'll need to get to the number to tell exactly what they where when new. Some believe the TRS is a stronger unit but parts availability is becoming an issue for sure. The biggest advantage to the bravo drive is no transmission needed. However when changing to the bravo and eliminating the trans some drive shaft work needs to be fabricated or engines need to be relocated. That's what I think I know.

The ID is under the decal on starboard side.You must remove the decal to see it.Some had a decal on the back cover on the upper that had the serial number on it.TRS's came in 2 designs.1973-76 and 77 to 93.Second design is best.First is getting very hard to find parts for.Actually uppers are the same,lowers are different.Cyclones were a series of engines Mercury made back 70's-80's 400, 440 and 460 HP.If unable to see serial numbers the only way I know is to pull the prop shaft and get numbers off bearings in lower to ID year.Shaft spline are all the same.Just to let you know the decal set is $160 bucks!!

It looks like i will have to remove layers of paint to eventially locate the s/n . These are boat less and do plan to buy project boat with at least one on the stern. I would say the legs are late1980 to 1993 production. At least there is no dog clutch. Should the bearings be able to be sourced via a bearing distributor or are there some that are merc specific? The hydro rams , can any other be used than the TRS? I appreciate your assistance.

All the bearings are tapered Timkin except 2 which are straight roller Torrington's.I was able to purchase all except for 1 of the Torringtons.It is the lower drive shaft pinion bearing.It was $106 from Mercury.All the others I purchased for about 1/2 of Mercury's prices from a bearing distributor.The TRS drive uses a transmission.If your drives have a drive shaft with external splines it uses a Borg Warner trans.If they have drive shafts with internal splines and a spring on the end they use a Merc Trans.The engine has to set a foot farther forward due to having a transmission.I read one time on a post here where someone used bravo cylinders on a trs but had to do some grinding to make a hydraulic line clear.