That's not a military 50 hp outboard. J40RLEIA is a long shaft recreational 40 hp from 1991. Go to this link, and you'll find your model number in the list under recreational outboards. You can get a manual from an Evinrude dealer.
There is no military model with that model number, and if it says J40, it's a Johnson 40 hp outboard. The A is just a model run number. EI is 1991. R is rope start. L is long shaft.
http://www.skoterskroten.com/img/arsmodellstabell.pdf