The Ulster coach can also call on prop John Afoa who has returned from New Zealand. The All Black replaces Declan Fitzpatrick who has been ruled out after suffering a neck injury during a scrum last week against Glasgow.
Best's inclusion at hooker sees Andi Kyriacou drop out of the match day squad, as Nigel Brady retains his place on the bench. Ferris and Henry join Pedrie Wannenburg an experienced back row.
Craig Gilroy is named on the left wing in place of Scottish international Simon Danielli, who misses out on a squad place. The backs remain otherwise unchanged but Ruan Pienaar is named on the bench, despite not being named in the preliminary squad.
The scrumhalf has been ruled out since picking up a hamstring injury against the Scarlets at the end of October.
Ulster will find comfort in returning to Ravenhill this week, where they have lost only once in their last 12 encounters. Scarlets are one of the form teams in Europe at present, and are undefeated in their last eight matches in all competitions since their 10-20 loss in Treviso on 1st October.
Scarlets won 24-17 at Parc y Scarlets when the two teams met in the RaboDirect PRO12 on 29th October, but the Welshmen have not won in Ireland since a trip to Connacht on 9 January 2009.
There are still tickets available for Friday's game. They can be bought online at www.ulsterrugby.com or by calling the ticket office on 02890493222 (ticketing option). Alternatively, you can pay at the gate on match night.
Please be aware that ticket zoning and scanning will be in operation at the ground this season. Supporters should check their tickets to ensure that they are entering through the correct gate. More details are available at http://www.ulsterrugby.com/news/9575.php.
Ulster Rugby would advise supporters coming to the game (gates open 5.30pm) to avoid parking in the immediate vicinity of the Ravenhill Grounds and that the following roads are only accessible for residents and closed to everyone else:
1. Onslow Parade
2. Ravenhill Park
3. Ravenhill Park Gardens
There will also be parking restrictions in place in the Castlereagh area (Mount Merrion Avenue). Supporters are encouraged to make use of the Park 'n' Ride facilities at Pirrie Park and along Montgomery Road.
Ulster Match Day Squad to face Scarlets, Friday 2nd December, Ravenhill (kick-off 7.05pm)
(15-9): A D'Arcy; A Trimble, D Cave, N Spence, C Gilroy; I Humphreys, P Marshall;
(1-8): T Court, R Best, J Afoa, J Muller (capt), D Tuohy, S Ferris, C Henry, P Wannenburg;
Replacements (16-23): N Brady, P McAllister, A Macklin, L Stevenson, R Diack, R Pienaar, P Jackson, I Whitten
Unavailable due to injury: Jared Payne (achilles), Declan Fitzpatrick (neck), Paddy Wallace (thumb)
63x46.png){kind=logo}