Head Coach Lee Johnson has had mixed news elsewhere, though, with Bailey Wright ruled out and in-form winger Jordan Jones a major doubt.
Jones was suffering from some muscle tightness in the latter stages of the 2-0 win over Portsmouth, a game in which he produced both a goal and an assist.
The winger will face a late fitness test alongside Aiden O'Brien.
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Leadbitter suffered a dislocated shoulder in the 2-2 draw with Crewe Alexandra late last month but told Johnson he would play through the pain abrrier after getting the go-ahead from a specialist.
It gives the boyhood Sunderland fan a chance to play his part in securing silverware for the club and also boosts the Head Coach's options given that Carl Winchester, so impressive at Fratton Park earlier this week, is cup tied.
"I think he's ready," Johnson said.
"Grant will absolutely be in the squad, he's trained for the last three or four days. I think he's been trying to get up close and personal in traininto make sure he's tested it, and he looks good.
"He's got a level of protection with a sort of light brace that he has, just to help protect certain movments.
"I think he's OK and I wouldn't have any fears putting him on the pitch.
"Aiden O'Brien will have a fitness test on Saturday," Johnson added.
"We'll give him as long as possible.
"Jordan Jones is similar and we're not sure if he'll be available, he's going to have a fitness test.
"I'd say he's probably less likely to be available than Aiden."
Johnson has mixed news in defence, where his options have recently been heavily depleted.
Dion Sanderson and Jake Vokins are both cup tied alongside Winchester, while Wright is not yet ready to return from a calf injury.
The experienced defender is on schedule in his recovery and Sunday's game has come just too son.
The return of Tom Flanagan on Tueday night was boost and Johnson also expects the experienced and versatile Conor McLaughlin to be fit for Wembley duty.
"We're slightly depleted but we are hopeful of a couple returning," Johnson said.
"Conor McLaughlin should be back if we need him, so that's an important one for us.
"Bailey Wright is out."
In a significant boost to Sunderland's long-term prospects, Denver Hume is closing in on his return from a hamstring injury.
Given that there were at one stage fears that he could be ruled out intil at least the middle of next month, his return in the coming weeks will some welcome quality and energy to the squad.
"Denver Hume is nearly there but this game probably comes a bit too soon for him," Johnson said.
"I've been very pleased with his movement and his progression over the last couple of weeks."
Tranmere Rovers boss Keith Hill confirmed today that he will be without James Vaughan, Sid Nelson and Otis Khan for the final.