wideband size issue

Picked up an aftermarket turbo elbow, wideband i have is much too small for the bung thats in it… the bung out of the stock elbow is much too big… ive gathered that the common size for o2s are m18x1.5? where can i find a bung to fit my o2 sensor? i have spent hours in plumbing looking through bushing… my wideband fits into a 1/4" bushing… but the thread on my elbow seems to be in between 3/8" and 1/2"…
suggestions?

Just realized my “wideband” is a stock “skinny” red top 02 sensor…
i now have 2 options…
a) apparently the o2 sensor bung of a ka manifold will help my situation… m12x1.25 female to m18x1.50 male… true?
or b) find a m18x1.50 bolt or drain plug and drill/tap it… finding an m12x1.25 tap maybe not so easy… help?

Check out an exhaust shop, they may have one that fits. Also check Lowes if there is one near you, they have speciality bolts that might work.