Engineers could make these stations for 100 fuel and 300 manpower, or it could be a upgrade to the tier 3 building (Just throwing a price here).
Players could drive their t34/76 to this station and upgrade them to t34/85 for 100 munitions or so (All players could use the same station). Upgrading the tank would take about 90 seconds.
This would add more reasons for making t34/76 tanks.
This is what it could look like, i know those are not soviets.