Nikor stainless steel reels and tank

Hello !
I've got a couple of Nikor 4x5 reels. Each came with it's "matching" tank. One is taller than it's brother, so I wonder why.
Could someone tell me how tall are 120/620 reels and if they are same diameter as the 4x5 reel ?
Because I suspect that I've got one 4x5 tank and one 120/620 tank.
Many thanks in advance for your help !
P.S. Do you know where I can get plastic caps to close the cap in order to use the tank by inversion ?

Nikor made 2 similar 4.5-inch diameter tanks: the 4x5 reel is designed to fit the 4.7-inch tall tank, and two 220 film reels (the larger 4.5-inch diameter reels) fit the taller 5.6-inch tall tank.

The Nikor tanks with the smaller stainless steel cap were designed for inversion. But in practice, I find I must hold the cap on tightly during inversion.

Nikor tanks all leak, but I wouldn't use any thing else.