Google is your friend. Here is a link to a tech article I found by simply searching google for MY6 transmission. Remember there is a ton of information out there and available to find if you only search.

http://www.customclassictrucks.com/..._speed_overdrive_transmission/index.html

of course you could also pony up about $3000 for a tremec TKO 500 transmission, but the A833 is a more affordable alternative. It will be necessary to machine the front of the A833 transmission to fit. Again, do a search on this site or others, there is a ton of information on swapping the MY6 transmission.