Sewer Line Clog suggests pipeline replacement
Loosen with a pick or mattock, move with a shovel, and be very careful of that gas line. Find the sewer line first from the side the gas line is not supposed to be on. 2 feet deep is easy.

If things are frozen now (I don't know where you are, since you didn't say) it will be more difficult to dig, but it can be done if needed. Otherwise wait for spring.

I'm not certain what the best approach to splicing the line in place would be. I'd guess 2 rubber couplers, because the still-buried pipe will not want to move. Mind you, at that age I'm also concerned with the distinct possibility that you might have 10 feet of cast iron and then change to Orangeburg (tar-paper) pipe, which is useless stuff by now (it ages poorly and age is upon it) and would involve digging up the whole run.

Bedding is important because otherwise that 5 feet can deform and interfere with correct flow in the pipe.