Hi guys ,
Ive got a drive unit right side Fr wheel 67123-80 AMF packaged . does anyone know what ratio this thing would be ?

reason being I want to put a 21" HD on the back of a 25 scout but Im gonna need a left side drive unit which means figuring which drive to which speedo
I need to flog this one off because chain is on the right side so its no good

any reason why these are specific to a side of wheel ? can they be driven back wards ?   its just a worm gear innit ?
cheers

this is what I find but not specific to the p/n ..... cant find yet

Right side = 67127 - 73 = 2.625:1   FX FXR XL  , 19" wheel  , 1973 to 83
Left side = 67127 - 84A = 2.625:1  FX FXR XL , 19" wheel , 1984 to 94

Right side = 67073 - 81 = 2.75:1  FL FLT , 16" wheel , 1981 to 86
Left side = 67073 - 87A = FLHS , 16" wheel , 1987 to 95

continuation of part numbers and swap from right to left sides . Im guessing p/n 67123 - 80 is alternative to 67127 -73 with a japanese production . forks , brakes and electrics were made in Japan anyway . the rotation of the drive is beyond 2.5:1 so its gotta be 2.625:1 . maybe its to convert 1984 to 94 to RHS speedo ?

Im only familiar with the 1:1 , 2:1 and then the 2240:60 pops up which is confusing but its been around 30 odd years .
because I have shovel the speedo drive is in the trans so I never pay attention to wheel drives .

apparrently Jap bikes use 2240:60 ....why it isnt written as 37.33:1 ?
remembering the Japs make wheels , brakes , forks , ign , starters , alternators for HD

Im thinking the speedo has the actual 1:1 , 2:1 ratios and then the different drives are mated to "1:1" , "2:1" , "2240:60"  but they have the odd ratio like retrocycle list below , because when I turn it 1 revolution the spindle drive definitely turns 2.625:1 not 2:1 , 2.5:1 or 2.75:1

http://www.retrocycle.com/images/customchrome_catalog_2011/pimg1151.jpg