In the late 1990's RCF, under the auspices of a UN-assisted program, came out with some prototype coaches of new designs, classified IRX/IR15 (IRW?), IRY/IR20, and IRZ/IR30. The first part of the code (e.g., IRY) refers to the shell design, and the second part (e.g. IR20) to the bogie design.) The IR20 bogies are based on the Eurofima design (in fact, they are said to be more or less an exact copy of the design).
The IRW coach is said to have had a variety of passenger-friendly and track-friendly features such as chemical toilets. As its production costs were projected to be too high, this design never entered serial production. The sole coach of this design made by RCF never entered service...
more...

with IR (and is still [12/04] at RCF). The IRZ coach is said to have encountered various design problems and was abandoned after a few trials.
The IRY/IR20 coach, which was designed for a max. speed of 140km/h, did enter serial production in small numbers (more below). One or two isolated examples of other RCF-built coaches with features different from the normal ICF coaches have been spotted on rare occasions (e.g., there is a report of one 3A coach used with the Grand Trunk Express in 2001), although information about these experiments (which is presumably what they were) is very sparse.
Some of the IRY/IR20 coaches, with a ribbed or corrugated shell design for strength, were used for a while ([2/02] and are still used occasionally) with the Amritsar Swarna Shatabdi. Another rake of IRY/IR20 coaches was being used for the Bareilly Shatabdi. Apart from that these coaches do not seem to be in use elsewhere [5/01]. Update [12/04]: One of the IRY/IR20 rakes is no longer in service, being cannibalized as a source of spare parts for the second. Improvements in these IRY/IR20 coaches include better ride quality, larger windows, improved noise reduction, improvements in the air-conditioning system and ducts, and modified pantry equipment including trolleys, drink dispensers, etc. The bogies for these (IR-20) will continue to be manufactured for use with MG coaches with service speeds of 100km/h, besides also being exported (Vietnam, some African countries). Meanwhile for coach bodies/shells, RCF has switched to production of the LHB coaches (see below).
In November 1999, ICF manufactured an AC-2T coach fabricated out of stainless steel. This sole prototype has not been followed up by more units.
---------------------------
Source: IRFCA