What year is 351 windsor D9te6059b?

You are looking at a timing cover from a 1979-mid 80's Ford 302 or 351W. This can be determined by the 6059 intermediate number.

to determine what year and month the timing cover was cast look for a two-digit year code 80, 81, 82 etc. in a "sundial". the sundial will tell you which month is was cast.

that cover will bolt onto any ford 289,302, 351W from 1963-1996.

In order to verify the date and identity of the engine itself, please remove the starter and look at the engine block number hidden there. The correct number will have a 6050intermediat number. there is often a date code there which will read number, letter, number number... that can help verify the value and application.