The final salvos in the 4 1/2-month-old war for Paramount Communications are expected to be fired today. But while Viacom and QVC have until 5 p.m. this afternoon to put their final and best bids on the table, Wall Street was unnerved Monday by speculation that QVC may not increase its offer.“We expected QVC to make some kind of announcement, even if it just said another announcement was coming,” said one rattled arbitrager. With both tender offers scheduled to expire at midnight last night, sources did not think QVC chief Barry Diller would chance letting Viacom get the 50.1% of Paramount shares needed to be declared a winner. But sources close to QVC said that Diller is very reticent about upping his offer, believing it still the best bid on the table regardless of the endorsement by Paramount board of directors last week of Viacom’s revised bid. Based on Monday’s closing prices, analysts valued QVC’s bid at about $ 85.62 a share or $ 10.1 billion compared to Viacom’s at $ 79.92 a share or $ 9.5 billion. But traders are said to prefer the Viacom bid because of its higher cash component ($ 107 vs. QVC’s $ 92) and more protection on its back end. A QVC board meeting held Monday afternoon resulted in no public action. “Barry is very nervous about bidding against himself, and very concerned that if he loses, that he comes out of this with his reputation intact,” said a source close to QVC. Fear that QVC will not return to the bargaining table pushed shares of QVC up 25 cents to $ 44 while knocking 12.5 cents off of Paramount, which closed at $ 79.625. Accordingly, Viacom shares plummeted on the perception that it may be close to winning Paramount; its Class B shares dropped $ 1.25 to close at $ 34. 75. But while some speculate that QVC may have had enough, others say the company is just biding its time — knowing that the arbs will wait until final bids are in to tender — and will weigh in with a revised bid at the 11th hour. But if that should be the case, sources close to Viacom said they are prepared to further revise their bid.