How can I tell the difference between M70 and M73 engines

[djinnaroth]

as it is said in the title

how can i tell the difference just by looking at both engine,
without testing the car

[Ahmed303]

Probably the Engine Acoustics cover (unless it is changed). The M73 has a curved end by the firewall. I however recommend looking up the VIN #.

[TxGR8White]

Does the engine have air injection? if so, then it is an M73.
If the DK motors (throttle bodies) are still attached and the "motor" part is black, then it is an M70.