With the success of the U36C to SF30C program, the AT&SF turned its rebuilding prowess to
another class of General Electric locomotives. This time a smaller B-B locomotive class was
chosen, the U23B, with special attention to economic feasibility and locomotive longevity.
In the summer of 1987, the Santa Fe Cleburne Shops, located in Cleburne, Texas took ATSF U23B #6332,
and began the prototype program. ATSF #6332 was chosen for it suffered wreck damage, and thus became
the right locomotive at the right time for this particular rebuilt program.
In July 1987, the Cleburne Shops released the prototype for evaluation on the feasibility of a
rebuilding program for Santa Fe's remaining U23B locomotives. The ATSF #6332 was professionally
transformed into a new class, the SF30B [Santa Fe (SF), 3000 HP (30), B-B trucks (B)], and renumbered #7200.
The new SF30B prototype had numerous physical, cosmetic, and internal changes from its humble beginnings
as a U23B unit. For starters the locomotive's horsepower was increased from 2300 to 3000 hp, as the
Cleburne Shops installed a General Electric 7FDL-12F30UX prime mover. The electric systems were modified
to Dash 7 standards, and Sentry Wheel Slip capability was added. The original 3,250-gallon fuel tank was
maintained, however overall capacity was reduced to 2,900 gallons, as a section was used as a retention
compartment/tank. The fuel tank was also expanded into the frame, giving the 45 degree black angle into
the side sill. The fuel filler was also moved higher onto the side sill, however by November 1989, the
fuel filler was moved back to its former lower position. The crew cab dimensions remained the same,
however was moved forwarded in order to house a new electrical control cabinet. The cab also received a
Cleburne-manufactured nose - similar to the one constructed for the SF30C. The new SF30B also lost its
original front and rear drop steps - in favor of anti-climber pilots.
In the engine area, the oil-bath air filters were replaced with paper filters, and the radiator section
was completely Cleburne-fabricated, giving the locomotive a very unique end profile - complete with crew
ladder instead of grab irons. The radiator area, although completely reconstructed still held the same
amount of cooling water - 350 gallons. The roof was also unique as the new primer mover contained a new,
oversized exhaust stack, which can also be found on the Dash 7 model. Operating in the arid desert, Santa Fe
also added a cab air conditioning unit, as well as repositioned the horn. To lessen the wear of the wheels on
rail curves, a flange lubricator tank was also added behind the cab on the conductor's side.
Originally, the SF30B rode on AAR type "B" trucks, however by 1993, the floating bolster trucks from the
retained B39-8, #7401, were utilized, and by 1996 the SF30B was outfitted with ditch lights.
Overall the prototype SF30B was deemed a success, however by this time, the age of contracting locomotive
maintenance outside of a company had become a way of life, and the Cleburne Shops were closed, leaving #7200
as the only one of her kind. General Electric was contracted to maintain Santa Fe's GE-built locomotives, and
this included the SF30B, although the rest of Santa Fe's U23B fleet had been purged from the roster. In order
to maintain a general maintenance schedule, the SF30B was renumbered into Santa Fe's fleet of B23-7 locomotives,
and given a new number, #6419. General Electric also derated the horsepower of #6419 from 3,000 back to 2,300
horsepower, as GE did not wan to be responsible for the possible stress caused by the former high rating.
The SF30B made it through another purge during the combination of diesel fleets when Santa Fe merged with
Burlington Northern to form the expansive BNSF Railway. The new company renumbered the unique locomotive once more,
and today wears #4276, and can be found in regular BNSF manifest freight, and local, service.