To determine the age of any OMC outboard made since 1980, look at the model number.
The last 2 characters are the last 2 digits in the model year, well it is in code!
Write out the word INTRODUCES, then underneath write the numbers 1-0, so that 1 is below I, 2 is below N, until you get to 9 is below E and 0 is below S. The model year can then be read,
example....my 9.9hp is model # J10RET.
This translates as J = Johnson ( E = Evinrude) 10 = 9.9hp R = rope start, then the last 2 characters (ET) corespond to E = 9 T= 3 or a 1993 model. My 4hp ends with "SI" or 2001, (S= 0, I= 1).
If your motor is an 8hp, it will not be newer than 1984 (the 1980-83 would be 7.5hp)
The 8hp Johnson weighs 56# for the short-shaft, 59# for the 20" long-shaft, or 64# for the "Sailmaster" 25" X-long-shaft.