An equine head case with a penchant for running second, a 10-year-old gelding backing up after a barnstorming run at Scone and an eight-year-old resuming from a long spell.

These are the ingredients that has Mudgee trainer Mark Milton thinking he might have a mixed day at the office at Orange on Sunday.

Milton saddles Cob, Gold Sultan and Series and says there are plenty of arguments for and against the unlikely trio.

He says Cob, a lightly-raced four-year-old who has 59kg in Sunday's GB Auto Electrics Maiden Plate (1300m) and placings at five of his past six starts, still needs to develop mentally.

"Mentally immature is the only way to describe him. He's a four-year-old going on one, but I suppose four seconds in a row is better than four lasts in a row," Milton said.

Milton said Cob, part-owned by the trainer, has been his own worst enemy in recent starts.

"A couple of times he's looked all over a winner but has just got nutted on the line. We've tried a few things with him, but he still seems to find second and third placings rather than first," Milton said.

Stable patriarch Gold Sultan backs up in the 1400m CUB Spring Thaw Handicap after running a slashing fourth to Double Five at Scone on Tuesday.

"He ran a really good race and he's done well since," Milton said.

Series, an eight-year-old by Redoute's Choice, hasn't appeared since finishing down the track at Bathurst last November.

He will resume in the Tilston's Bec Gold Rush Handicap (1000m).