Hi Martin,
welcome to Unimog Club Uk.
regarding the linkage you should already have the bracket to the left of the diff (looking from the back) on the axle, the rest is bolt on and easily removed if you plan to go offroading.
regarding the side belt pto, i think Manfred is selling just the pully? but the side pto's are quite rare, we have a friend with one on his 411
