You can find updates to the original retail, including the Gold edition patch, here.
Note the GOG.com version is fully updated, thus these are unnecessary if purchased from there.
Nitro also has a Patch I & II, though these were only ever beta. Instead use the Unofficial Nitro Patch III.
See Rainbow color problems in older games.
C:\Program Files\Activision\Interstate '76\
"This problem can be fixed by retrieving the I76shell.dll from the 1.06 or 1.08 patch for the original I76 W95. Do not install the 1.06 patch to the Gold Edition! It will crash. Instead, extract the 1.06 patch to a new folder. Copy the I76shell.dll file to the Gold Edition directory. Only 1 file will be replaced.
I tested Gold i76 using the i76shell.dll file from the 1.083 patch. It worked! I was able to get into the 13th level without a page fault crash. Be sure to back up the original .dll file though before doing this. The Gold edition will crash on Instant Melees with 1.08 .dll file installed. I would only use the 1.08 file temporarily for the purpose of gaining access to the 13th level."
if exist I76shell.bak goto error
ren I76shell.dll I76shell.bak
ren I76shell_1083.dll I76shell.dll
echo Mission 13 Fix already enabled! If you are experiencing crashes in
echo melee or other single player missions, run RevertM13.bat instead.
echo Mission 13 Fix enabled. Run RevertM13.bat to disable.
if exist I76shell_1083.dll goto error
ren I76shell.dll I76shell_1083.dll
ren I76shell.bak I76shell.dll
echo Mission 13 Fix NOT enabled! If you are experiencing crashes in
echo mission 13, run EnableM13.bat instead.
echo Mission 13 Fix reverted. Run EnableM13.bat to re-patch.
See Force CPU affinity.