The standard fox top hat bushes (silver) are a push fit and are normally pretty tight in the DU. Of course this then rotates up against the mounting point on the frame or link as the suspension moves which has always struck me as a bit odd but that is the way it is.
imo replacing the bushes with Tftuned heavy duty ones is a good idea as they are designed to allow the bush to rotate on itself and perhaps provide better suspension performance as that is less friction.
Ideally you do need a tool to hammer out the DU, but you could save money and replace only the end that attaches to the upper link as that rotates more than the frame end.
mk1 nomads use 22mm 3/8″ bushes not sure on mk2s.