RS485 transceiver.

I am working on a project which requires me to work with a RS-485 transceiver and J1708 protocol(for heavy duty vehicles). We found two RS 485 ICs specifically designed for J1708-DS36277 and MAX3444E.The former costs about Rs 118 and the latter costs Rs 630. The one extra feature in the Max IC is +/- 60V fault protection. Can anyone tell me what is fault protection and is it worth spending so much on an IC which has this feature?

Your call... Heavy duty vehicles cover a wide range... if an alternator goes ping on a 24v system... you may be able to see spikes up to 48v + a/c. that would damage commercial spec chips

It's also Completely common for the serial port (usually tx) to get burned when the level shifter goes. I prefer much more robust TVS/MOV devices or zener & schottky diodes, depending on situation.

Cars can easily see -200 to +50 V spikes from the alternator. Trucks, probably higher.