Alan,
There was an article in OST on building the pickle tank "tub" cars quite a few years ago.
You might 1st pull up the indices of that publication and extract that article - it's quite good. I built 2 cars - one of each gallon capacity.
If you are more than passingly interested in this topic, request from the NMRA library copies of the SIG newsletters on the topic of every pickle industry related. "Pickles in Miniature"
In those newsletters you will find all of the information regarding roster names and numbers, sizes of tubs (2 different gallon sizes...), dates of use and most importantly --> the plans for these cars and the coffin cars and the vinegar tank cars.