I had a cost and task tracking sheet in Excel. My hard drive crashed and it took the files with it. But the set up was similar to what you’re looking for. I had a tab for each system listed in the service manual such as Engine, heating, cooling, brakes, etc. On each page there were column headings for repairs, maintenance, and upgrades. Under those columns were sub columns such as issue symptoms, issue cause, issue repair notes, part numbers, and repair costs. On the last tab all the costs were auto filled from the previous tabs so that I could see total costs by repairs, maintenance, and upgrades.

I even inserted pictures of the steps I took to do repairs or maintenance so I would remember how things looked when I was performing the repair or maintenance.

The sheets are not hard to build, should take about 30 minutes to create if your familiar with excel.