The truck will handle the trailer. It will not be a speed demon on the hills, but it will pull it.

If you are going to be pulling weight often, you may want to add a turbo, it is worth it's weight in gold.

The manual trannys were great.

The only issue motor wise is cavitation, this happens when proper coolant addatives were not used.
155,000 is just broke in good if it was properly maintained.