The air reservoir tanks on my truck (2007 KW T300) are starting to leak from corrosion as is expected here in the Midwest on a 17 yr old truck. Kenworth apparently wants $630 for each one and there are 3. Outside has 2 ports, one in the middle with a plug and the bottom one is a drain valve. Inside has Five 1/2” ports and one 1/4” port. 8” diameter and 25” long, strap mount under the battery box. I’ve dug around on Dorman’s site and can’t come up with one I’m satisfied will replace them. Hate to bite the bullet on $1900 for air tanks but I might have to. Anyone got any other options??