MB D309 diesel bus info request

I've found a 1975 D309 bus for sale, 4 cyl. diesel automatic. Looks like it'll make a great camper. Can anyone tell me about this vehicle? Is it reliable, are parts available, etc... I'm able to do basic repair/maintenance but I'm not the kind of person who spends my weekends under my rig and I don't want to become one. The bus has low mileage - 50,000 - and apparently was a MB company vehicle. thanks, tommus