None of the Heritage car fleet was painted in Phase V. That paint scheme was only on some Amfleet cars and was meant to correspond to the Acela branding when those trains came online. Phase VI is the current Amtrak scheme that made it onto some of the Hertiage fleet cars. The website has since been updated to reflect this.
Amfleet Phase V Paint Scheme
Correct, no phase 5, but here is the phase 4 info. Heritage diners wore phase 4 and were in service in the LakeShore, and Silver service trains. I include a link to my own video shot in Cleveland in 2014 (not a great video but was an impromptu catch of a daylight visit in Cleveland). Four 10-6 sleepers were rehabbed in 1998 for the Three Rivers. They wore phase 4 fresh paint and were in service until 2003. See pic. Also there was a series of "Grove" 10-6 sleepers done in phase 4 prior to 1998. 2 of these were refreshed for the Three Rivers.
Three Rivers sleepers:
#2466 "Silver Plain" (former CB&Q car)
#2450 "Beech Grove" (former SP but named by Amtrak)
#2440 "Pacific Beach" (former UP)
The 4th car for the Three Rivers was either Cyprus or Birch Grove.
I do know that #2451 Birch Grove and #2446 Cypress Grove wore the phase 4 paint prior to 1998, just like the above listed cars which were refreshed for the Three Rivers. The ex SP cars had a larger name block placed on the former large SP plaquard center car. Silver Plain and Pacific Beach had traditional name plate.