Lorimar TV remains the 800-pound gorilla of prime time, with 13 series set for next fall on the three networks and Fox Broadcasting Co., even as network in-house production continues to squeeze opportunities for new product.Lorimar not only easily led the way among individual production entities but ranks as the leading outside supplier to all three major networks. Combined with Warner Bros. TV, HBO Independent Prods. and Witt-Thomas Prods., Time Warner production units will provide 20% of the 93 regular series (excluding “Monday Night Football” and movie slots) scheduled for next fall. In fact, Time Warner will practically own Friday night, with four shows from the studio (Lorimar’s “Against the Grain,”"Family Matters” and “It Had to Be You” plus WB’s “The Adventures of Brisco County Jr.”) slotted against each other in the 8 p.m. slot. The networks, meanwhile, haven’t dramatically increased production output through their in-house entertainment divisions (they combined for 12 shows last fall, the same as next season) but are eating up big chunks of prime time with news magazines, which account for three hours on each of the Big Three webs and another on Fox. Excluding “Monday Night Football,” which is produced through ABC Sports and takes up two additional hours of prime time through the fourth quarter, the three networks will supply 21 shows totaling 18 hours, exactly one-third of the 54 hours on the Big Three not accounted for by movie slots or football. In a similar vein, in-house Fox divisions (Twentieth TV, the Fox Television Stations and Fox News) will produce six shows, or one-third of Fox’s 18 series not counting its soon-to-be-weekly movie, comprising 38% of its 15-hour-a-week prime time lineup. The major studios, including Fox, continue to account for over half of all prime time programming but have clearly seen their percentages cut into by network reliance on in-house production — especially the news shows, which each eat up an hour of prime time. Last fall, there were only six prime time news shows filling a half-dozen hours, a figure that swells to 10 next September, with two more in reserve for January ’94. According to a tally of fall shows, the majors (Time Warner, Disney, Sony divisions Columbia and TriStar, Fox, Paramount and Universal) combined will produce 51 series (or 55% of all those scheduled for fall) totaling 34 hours next fall, or 51% of all time allotted to regular series programs. MGM TV, which has shut down its TV division, provides one additional hour on a hold-over basis , CBS’ “In the Heat of the Night.” Fox could also add another show to its column if it becomes a partner on “Townsend Television,” a one-hour variety show currently being produced solely through Robert Townsend’s Tinsel Townsend Prods. Those studio figures aredown somewhat from last year, and several of the majors — fearing a loss of opportunity as the networks, with relaxed financial interest and syndication rules, expand more into production — have thrown more of their resources into first-run syndication. Programs produced through studios sold directly to stations include Paramount’s syndicated “Star Trek” combo and “The Untouchables,” Warner Bros.’ Prime Time Entertainment Network (both Lorimar and WB TV produce hours for that block), and planned first-run offerings from MCA/Universal and Columbia. Universal placed only one new series on the fall roster, the Steven Spielberg/Amblin TV hour “seaQuest DSV,” but has a midseason order from Fox on the superhero series “Mantis” and will intro another Fox show, “Danger Theater,” this summer. In fact, Warner Bros., Universal, Paramount and Spelling are all down two shows compared to their tally last September. The two leading suppliers, Lorimar and Disney, were also the most successful in terms of landing new series on the air, placing seven and three new shows, respectively, on the fall rosters. A total 39 new series are scheduled for September, six more than last season, before Fox introduced its Tuesday lineup. Lorimar also has a back-up order on the CBS reality show “How’d They Do That? ,” while Disney has its comedies starring Ellen DeGeneres (ABC), John Caponera (NBC) and Henry Winkler (Fox) in reserve, as well as a 14-episode pickup from ABC on the returning series “Dinosaurs.” Sony divisions Columbia and TriStar will be involved in at least seven series and will each produce one spoke of NBC’s “Mystery Movie” wheel — respectively, a “Hart to Hart” revival and the Larry Hagman vehicle “Staying Afloat.” Viacom provides another component of that franchise, “Perry Mason,” while a fourth, featuring Kenny Rogers, will come from his production outfit and Dean Hargrove Prods. Columbia has also partnered with NBC Prods. on the Bill Cosby mystery movies and will provide Fox at least three vidpix featuring Ron Silver as “The Good Policeman” (see related story). In addition to its fall comedies, NBCP also has a midseason sitcom for the Peacock, the Gene Wilder vehicle “Eligible Dentist,” and is involved as a producer partner in each of its summer serials under the “Great Escapes” umbrella. The producers with the busiest phones will be Witt-Thomas Prods., producing a total of five fall series plus another (Fox’s “My Kind of Town”) as a midseason backup. Like Steven Bochco Prods.’ relationship with Twentieth TV, the company has a distribution-only agreement with Warner Bros. Inc. and thus remains creatively independent from other studio units. Only one Witt-Thomas fall series, “The John Larroquette Show,” comes under its Warner Bros. pact, but the company still produces a quartet of comedies (“Empty Nest,”"Nurses,”"Blossom” and “Herman’s Head”) covered by its previous overall deal at Disney. Lorimar’s Miller-Boyett tandem again has four sitcoms scheduled, including three-quarters of ABC’s “TGIF” lineup. Fred Silverman will produce two regular series, “Matlock” and “In the Heat of the Night,” as well as the “Perry Mason” movies and “Diagnosis Murder: Starring Dick Van Dyke,” to air on CBS this summer. Castle Rock also expanded on its “Seinfeld” base with two new sitcoms to lead the independent charge, although Spelling TV has a third hour, NBC’s “Winnetka Road,” waiting for an on-air berth along with its Fox tandem “Beverly Hills, 90210″ and “Melrose Place.” Several new suppliers made this year’s schedule, such as Kushner-Locke Co. and the Konigsberg/Sanitsky Co., both principally suppliers of TV movies. The latter’s series, “Angel Falls,” will be distributed through ACI, a consortium of independent producers of which the company is a part. Breaking down program genres next fall, while reality programming has decreased, variety has made something of a comeback with ABC’s “Paula Poundstone Show” and Fox’s “Townsend Television” joining “In Living Color.” Two dozen one-hour dramas are scheduled on the four services, the same as last September, while 47 sitcoms are scheduled, one more than last year.