Simplicity 5399 vintage sewing pattern, dated 1981
Men's Fuss-Free Fit Pants, In Two Lengths and Shorts:
Straight leg pants V. 1, Bermuda length V. 2 and shorts V. 3 have fly front, yoke and pockets, waistband, carriers and optional back welt pockets with flaps.
Size 36 - 44 (US)/ 46 - 54 (EUR)
Pattern is UNCUT and factory folded. Envelope has some shelf wear.
More men's patterns here:
https://allthepreciousthings.com.au/collections/men