Coolant capacity?

[Nested69]

Hello all, I have a 1969 Plymouth RR 383 automatic, with a 4 bl. I just flushed the radiator, and the engine. I was only able to get around 2.5 gallons of coolant back in it. To be honest, not much came out when I drained the radiator. This is after burping the system, with the heater on and off. I have read the system is supposed to take like 4.2 or so gallons. It won’t take anymore. The car is number matching and absolutely stock. It is not a AC car. Can anybody help me with this?

 

[69hemibeep]

Sounds about right. The heater core is full and you can only drain the block to the bottom of the water pump so the block is holding quite a bit yet.