Texas - The "welch" plugs for your 235 (both front and rear of block coolant core holes) is listed as GM# 3835121 and is 2" in diameter.

Dorman offers a replacement as Part# 550-028. This listing is for a package of 10, but you can purchase them from your local FLAPS for around $2 or less each. wink
Attachments

~ Dan
1951 Chevy 3 window 3100
Follow this story in the DITY Gallery
"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)