Stranger
But i think the top's too young (he's 18, and the bottom is early 30)
https://www.mangago.zone/read-manga/boku_no_omawarisan/ (ages 30 and 39)
Masculine bottoms:
https://www.mangago.zone/read-manga/under_the_green_light/
https://www.mangago.zone/read-manga/contradict/
https://www.mangago.zone/read-manga/the_mountain_branches_dream_of_goblins/
https://www.mangago.zone/read-manga/wet_sand/
https://www.mangago.zone/read-manga/flashlight/
https://www.mangago.zone/read-manga/on_doorstep/
https://www.mangago.zone/read-manga/joou_to_shitateya/
https://www.mangago.zone/read-manga/old_fashioned_cupcake/
https://www.mangago.zone/read-manga/tonari_ni/
https://www.mangago.zone/read-manga/mitsuya_sensei_no_keikakuteki_na_edzuke/
https://www.mangago.zone/read-manga/can_i_hold_your_hand/ (one shot)
https://www.mangago.zone/read-manga/i_m_an_old_man_but_also_a_saint/
https://www.mangago.zone/read-manga/confessions_of_a_35_year_old/
Oldman bottoms
Masculine bottoms
https://www.mangago.zone/read-manga/kiss_me_if_you_can/
https://www.mangago.zone/read-manga/unromantic/
https://www.mangago.zone/read-manga/boss_bitch_baby/
https://www.mangago.zone/read-manga/the_pizza_delivery_man_and_the_gold_palace/
https://www.mangago.zone/read-manga/omerta/
https://www.mangago.zone/read-manga/projection/
https://www.mangago.zone/read-manga/frey_drac/
https://www.mangago.zone/read-manga/starry_night/
https://www.mangago.zone/read-manga/introducing_my_manager/
https://www.mangago.zone/read-manga/a_guide_thicker_than_blood/
https://www.mangago.zone/read-manga/the_man_at_night/
https://www.mangago.zone/read-manga/romantic_captain_darling/
https://www.mangago.zone/read-manga/hell_intern/
https://www.mangago.zone/read-manga/off_track/
https://www.mangago.zone/read-manga/golden_pair_craeyon/
Looking for manga or manhwa:
- Young top, old man bottom recs (like The First of Summers)
- Masculine bottom recs (like Boundary of Delusion, Master-peace)