If you are looking for the best way to handle C18 v3.47 today, here are your most reliable options:
The is not the latest compiler, but it is the best for stability, speed, and predictability on classic PIC18 projects. For the embedded engineer who values "if it ain't broke, don't fix it," this toolchain represents a golden era of 8-bit development that modern IDEs have yet to surpass. mplab c18 347 full version best
Version 3.47 is often sought after for maintaining "legacy" codebases that were not originally designed for the newer XC8 architecture. It provides seamless integration with the older (v8.xx) and supports a vast range of PIC18 devices. For modern systems, Microchip classifies C18 as a Legacy Compiler If you are looking for the best way to handle C18 v3
Search the archive for "MPLAB C18" or "PIC18 MCUs" to find legacy installers. It provides seamless integration with the older (v8