The first coupler we installed took us the better part of 1/2 a day. The 20 or so after that took about 1/2 an hour.
When it comes to installing couplers, the first one is a real doozey! After that it gets much easier. The first one we had a handy back hoe. Worked but took a long time.
After that we would drag the coupler to the car with a come-a-long and drag it right up by running the cable over the bolster. When there was still room, we would insert the springs and spring blocks. Then we would grab the knuckle with an engine hoist, Ratchet both ends right up into place so we could install the block retainers from underneath.