Do your trim rams have both lines attached aft (front end)?
I rebuilt a set of trim rams with the aft line connections and the generic kit for 1970-1980 trim rams (Sierra) that supposedly had all the seals, was missing a couple of seals. I Emailed Sierra and they sent me a couple seal kits which solved the issue. A pain as it delayed the project, but 2 rams rebuilt for $40 was great.... Check your Mercruiser manual as it should have an exploded diagram of the rebuild process and seal location, will help identify if there are going to be missing seals from the parts kit.. These were trim rams off a 72 Mercruiser, MC-1. Here's the description of the kit I bought, google it.
P.T. O-RING KIT | GLM Part Number: 87410; Sierra Part Number: 18-2291; Mercury Part Number: 25-60342A2
The rams were pretty easy to rebuild, but I didn't have to figure with the end caps, they came right off with little effort. This was surprising as they were 40 years old, and I'm pretty sure they were virgin rams as the ols seals were as hard as a rock, brittle.